diff --git a/Makefile b/Makefile
index 3efdba9..f7a8532 100644
--- a/Makefile
+++ b/Makefile
@@ -29,4 +29,5 @@ lint_install:
 
 test:
 	go build -v .
+	go test -bench=. ./internal/checksum_test
 	#go test -v .
diff --git a/internal/checksum_test/sum_bench_test.go b/internal/checksum_test/sum_bench_test.go
index bfc0752..35ee021 100644
--- a/internal/checksum_test/sum_bench_test.go
+++ b/internal/checksum_test/sum_bench_test.go
@@ -28,6 +28,6 @@ func BenchmarkGChecksum(b *testing.B) {
 	}
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		checksum.Checksum(packet[i%1000], 0)
+		checksum.ChecksumDefault(packet[i%1000], 0)
 	}
 }
diff --git a/internal/gtcpip/checksum/checksum.go b/internal/gtcpip/checksum/checksum.go
index dfb4dd7..db03e64 100644
--- a/internal/gtcpip/checksum/checksum.go
+++ b/internal/gtcpip/checksum/checksum.go
@@ -38,3 +38,8 @@ func Combine(a, b uint16) uint16 {
 	v := uint32(a) + uint32(b)
 	return uint16(v + v>>16)
 }
+
+func ChecksumDefault(buf []byte, initial uint16) uint16 {
+	s, _ := calculateChecksum(buf, false, initial)
+	return s
+}
diff --git a/internal/gtcpip/checksum/checksum_default.go b/internal/gtcpip/checksum/checksum_default.go
index ea4585e..99a2d75 100644
--- a/internal/gtcpip/checksum/checksum_default.go
+++ b/internal/gtcpip/checksum/checksum_default.go
@@ -8,6 +8,5 @@ package checksum
 //
 // The initial checksum must have been computed on an even number of bytes.
 func Checksum(buf []byte, initial uint16) uint16 {
-	s, _ := calculateChecksum(buf, false, initial)
-	return s
+	return ChecksumDefault(buf, initial)
 }
diff --git a/internal/gtcpip/checksum/checksum_unsafe.go b/internal/gtcpip/checksum/checksum_unsafe.go
index 83f35c8..66b7ab6 100644
--- a/internal/gtcpip/checksum/checksum_unsafe.go
+++ b/internal/gtcpip/checksum/checksum_unsafe.go
@@ -1,5 +1,3 @@
-//go:build !amd64
-
 // Copyright 2023 The gVisor Authors.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/internal/gtcpip/header/ipv6_extension_headers.go b/internal/gtcpip/header/ipv6_extension_headers.go
index 3ab135d..20064d8 100644
--- a/internal/gtcpip/header/ipv6_extension_headers.go
+++ b/internal/gtcpip/header/ipv6_extension_headers.go
@@ -18,10 +18,8 @@ import (
 	"encoding/binary"
 	"errors"
 	"fmt"
-	"io"
 	"math"
 
-	"github.com/sagernet/gvisor/pkg/buffer"
 	"github.com/sagernet/sing-tun/internal/gtcpip"
 	"github.com/sagernet/sing/common"
 )
@@ -145,79 +143,6 @@ func ipv6OptionsAlignmentPadding(headerOffset int, align int, alignOffset int) i
 	return ((padLen + align - 1) & ^(align - 1)) - padLen
 }
 
-// IPv6PayloadHeader is implemented by the various headers that can be found
-// in an IPv6 payload.
-//
-// These headers include IPv6 extension headers or upper layer data.
-type IPv6PayloadHeader interface {
-	isIPv6PayloadHeader()
-
-	// Release frees all resources held by the header.
-	Release()
-}
-
-// IPv6RawPayloadHeader the remainder of an IPv6 payload after an iterator
-// encounters a Next Header field it does not recognize as an IPv6 extension
-// header. The caller is responsible for releasing the underlying buffer after
-// it's no longer needed.
-type IPv6RawPayloadHeader struct {
-	Identifier IPv6ExtensionHeaderIdentifier
-	Buf        buffer.Buffer
-}
-
-// isIPv6PayloadHeader implements IPv6PayloadHeader.isIPv6PayloadHeader.
-func (IPv6RawPayloadHeader) isIPv6PayloadHeader() {}
-
-// Release implements IPv6PayloadHeader.Release.
-func (i IPv6RawPayloadHeader) Release() {
-	i.Buf.Release()
-}
-
-// ipv6OptionsExtHdr is an IPv6 extension header that holds options.
-type ipv6OptionsExtHdr struct {
-	buf *buffer.View
-}
-
-// Release implements IPv6PayloadHeader.Release.
-func (i ipv6OptionsExtHdr) Release() {
-	if i.buf != nil {
-		i.buf.Release()
-	}
-}
-
-// Iter returns an iterator over the IPv6 extension header options held in b.
-func (i ipv6OptionsExtHdr) Iter() IPv6OptionsExtHdrOptionsIterator {
-	it := IPv6OptionsExtHdrOptionsIterator{}
-	it.reader = i.buf
-	return it
-}
-
-// IPv6OptionsExtHdrOptionsIterator is an iterator over IPv6 extension header
-// options.
-//
-// Note, between when an IPv6OptionsExtHdrOptionsIterator is obtained and last
-// used, no changes to the underlying buffer may happen. Doing so may cause
-// undefined and unexpected behaviour. It is fine to obtain an
-// IPv6OptionsExtHdrOptionsIterator, iterate over the first few options then
-// modify the backing payload so long as the IPv6OptionsExtHdrOptionsIterator
-// obtained before modification is no longer used.
-type IPv6OptionsExtHdrOptionsIterator struct {
-	reader *buffer.View
-
-	// optionOffset is the number of bytes from the first byte of the
-	// options field to the beginning of the current option.
-	optionOffset uint32
-
-	// nextOptionOffset is the offset of the next option.
-	nextOptionOffset uint32
-}
-
-// OptionOffset returns the number of bytes parsed while processing the
-// option field of the current Extension Header.
-func (i *IPv6OptionsExtHdrOptionsIterator) OptionOffset() uint32 {
-	return i.optionOffset
-}
-
 // IPv6OptionUnknownAction is the action that must be taken if the processing
 // IPv6 node does not recognize the option, as outlined in RFC 8200 section 4.2.
 type IPv6OptionUnknownAction int
@@ -294,143 +219,6 @@ func ipv6UnknownActionFromIdentifier(id IPv6ExtHdrOptionIdentifier) IPv6OptionUn
 // is malformed.
 var ErrMalformedIPv6ExtHdrOption = errors.New("malformed IPv6 extension header option")
 
-// IPv6UnknownExtHdrOption holds the identifier and data for an IPv6 extension
-// header option that is unknown by the parsing utilities.
-type IPv6UnknownExtHdrOption struct {
-	Identifier IPv6ExtHdrOptionIdentifier
-	Data       *buffer.View
-}
-
-// UnknownAction implements IPv6OptionUnknownAction.UnknownAction.
-func (o *IPv6UnknownExtHdrOption) UnknownAction() IPv6OptionUnknownAction {
-	return ipv6UnknownActionFromIdentifier(o.Identifier)
-}
-
-// isIPv6ExtHdrOption implements IPv6ExtHdrOption.isIPv6ExtHdrOption.
-func (*IPv6UnknownExtHdrOption) isIPv6ExtHdrOption() {}
-
-// Next returns the next option in the options data.
-//
-// If the next item is not a known extension header option,
-// IPv6UnknownExtHdrOption will be returned with the option identifier and data.
-//
-// The return is of the format (option, done, error). done will be true when
-// Next is unable to return anything because the iterator has reached the end of
-// the options data, or an error occurred.
-func (i *IPv6OptionsExtHdrOptionsIterator) Next() (IPv6ExtHdrOption, bool, error) {
-	for {
-		i.optionOffset = i.nextOptionOffset
-		temp, err := i.reader.ReadByte()
-		if err != nil {
-			// If we can't read the first byte of a new option, then we know the
-			// options buffer has been exhausted and we are done iterating.
-			return nil, true, nil
-		}
-		id := IPv6ExtHdrOptionIdentifier(temp)
-
-		// If the option identifier indicates the option is a Pad1 option, then we
-		// know the option does not have Length and Data fields. End processing of
-		// the Pad1 option and continue processing the buffer as a new option.
-		if id == ipv6Pad1ExtHdrOptionIdentifier {
-			i.nextOptionOffset = i.optionOffset + 1
-			continue
-		}
-
-		length, err := i.reader.ReadByte()
-		if err != nil {
-			if err != io.EOF {
-				// ReadByte should only ever return nil or io.EOF.
-				panic(fmt.Sprintf("unexpected error when reading the option's Length field for option with id = %d: %s", id, err))
-			}
-
-			// We use io.ErrUnexpectedEOF as exhausting the buffer is unexpected once
-			// we start parsing an option; we expect the reader to contain enough
-			// bytes for the whole option.
-			return nil, true, fmt.Errorf("error when reading the option's Length field for option with id = %d: %w", id, io.ErrUnexpectedEOF)
-		}
-
-		// Do we have enough bytes in the reader for the next option?
-		if n := i.reader.Size(); n < int(length) {
-			// Consume the remaining buffer.
-			i.reader.TrimFront(i.reader.Size())
-
-			// We return the same error as if we failed to read a non-padding option
-			// so consumers of this iterator don't need to differentiate between
-			// padding and non-padding options.
-			return nil, true, fmt.Errorf("read %d out of %d option data bytes for option with id = %d: %w", n, length, id, io.ErrUnexpectedEOF)
-		}
-
-		i.nextOptionOffset = i.optionOffset + uint32(length) + 1 /* option ID */ + 1 /* length byte */
-
-		switch id {
-		case ipv6PadNExtHdrOptionIdentifier:
-			// Special-case the variable length padding option to avoid a copy.
-			i.reader.TrimFront(int(length))
-			continue
-		case ipv6RouterAlertHopByHopOptionIdentifier:
-			var routerAlertValue [ipv6RouterAlertPayloadLength]byte
-			if n, err := io.ReadFull(i.reader, routerAlertValue[:]); err != nil {
-				switch err {
-				case io.EOF, io.ErrUnexpectedEOF:
-					return nil, true, fmt.Errorf("got invalid length (%d) for router alert option (want = %d): %w", length, ipv6RouterAlertPayloadLength, ErrMalformedIPv6ExtHdrOption)
-				default:
-					return nil, true, fmt.Errorf("read %d out of %d option data bytes for router alert option: %w", n, ipv6RouterAlertPayloadLength, err)
-				}
-			} else if n != int(length) {
-				return nil, true, fmt.Errorf("got invalid length (%d) for router alert option (want = %d): %w", length, ipv6RouterAlertPayloadLength, ErrMalformedIPv6ExtHdrOption)
-			}
-			return &IPv6RouterAlertOption{Value: IPv6RouterAlertValue(binary.BigEndian.Uint16(routerAlertValue[:]))}, false, nil
-		default:
-			bytes := buffer.NewView(int(length))
-			if n, err := io.CopyN(bytes, i.reader, int64(length)); err != nil {
-				if err == io.EOF {
-					err = io.ErrUnexpectedEOF
-				}
-
-				return nil, true, fmt.Errorf("read %d out of %d option data bytes for option with id = %d: %w", n, length, id, err)
-			}
-			return &IPv6UnknownExtHdrOption{Identifier: id, Data: bytes}, false, nil
-		}
-	}
-}
-
-// IPv6HopByHopOptionsExtHdr is a buffer holding the Hop By Hop Options
-// extension header.
-type IPv6HopByHopOptionsExtHdr struct {
-	ipv6OptionsExtHdr
-}
-
-// isIPv6PayloadHeader implements IPv6PayloadHeader.isIPv6PayloadHeader.
-func (IPv6HopByHopOptionsExtHdr) isIPv6PayloadHeader() {}
-
-// IPv6DestinationOptionsExtHdr is a buffer holding the Destination Options
-// extension header.
-type IPv6DestinationOptionsExtHdr struct {
-	ipv6OptionsExtHdr
-}
-
-// isIPv6PayloadHeader implements IPv6PayloadHeader.isIPv6PayloadHeader.
-func (IPv6DestinationOptionsExtHdr) isIPv6PayloadHeader() {}
-
-// IPv6RoutingExtHdr is a buffer holding the Routing extension header specific
-// data as outlined in RFC 8200 section 4.4.
-type IPv6RoutingExtHdr struct {
-	Buf *buffer.View
-}
-
-// isIPv6PayloadHeader implements IPv6PayloadHeader.isIPv6PayloadHeader.
-func (IPv6RoutingExtHdr) isIPv6PayloadHeader() {}
-
-// Release implements IPv6PayloadHeader.Release.
-func (b IPv6RoutingExtHdr) Release() {
-	b.Buf.Release()
-}
-
-// SegmentsLeft returns the Segments Left field.
-func (b IPv6RoutingExtHdr) SegmentsLeft() uint8 {
-	return b.Buf.AsSlice()[ipv6RoutingExtHdrSegmentsLeftIdx]
-}
-
 // IPv6FragmentExtHdr is a buffer holding the Fragment extension header specific
 // data as outlined in RFC 8200 section 4.5.
 //
@@ -473,242 +261,6 @@ func (b IPv6FragmentExtHdr) IsAtomic() bool {
 	return !b.More() && b.FragmentOffset() == 0
 }
 
-// IPv6PayloadIterator is an iterator over the contents of an IPv6 payload.
-//
-// The IPv6 payload may contain IPv6 extension headers before any upper layer
-// data.
-//
-// Note, between when an IPv6PayloadIterator is obtained and last used, no
-// changes to the payload may happen. Doing so may cause undefined and
-// unexpected behaviour. It is fine to obtain an IPv6PayloadIterator, iterate
-// over the first few headers then modify the backing payload so long as the
-// IPv6PayloadIterator obtained before modification is no longer used.
-type IPv6PayloadIterator struct {
-	// The identifier of the next header to parse.
-	nextHdrIdentifier IPv6ExtensionHeaderIdentifier
-
-	payload buffer.Buffer
-
-	// Indicates to the iterator that it should return the remaining payload as a
-	// raw payload on the next call to Next.
-	forceRaw bool
-
-	// headerOffset is the offset of the beginning of the current extension
-	// header starting from the beginning of the fixed header.
-	headerOffset uint32
-
-	// parseOffset is the byte offset into the current extension header of the
-	// field we are currently examining. It can be added to the header offset
-	// if the absolute offset within the packet is required.
-	parseOffset uint32
-
-	// nextOffset is the offset of the next header.
-	nextOffset uint32
-}
-
-// HeaderOffset returns the offset to the start of the extension
-// header most recently processed.
-func (i IPv6PayloadIterator) HeaderOffset() uint32 {
-	return i.headerOffset
-}
-
-// ParseOffset returns the number of bytes successfully parsed.
-func (i IPv6PayloadIterator) ParseOffset() uint32 {
-	return i.headerOffset + i.parseOffset
-}
-
-// MakeIPv6PayloadIterator returns an iterator over the IPv6 payload containing
-// extension headers, or a raw payload if the payload cannot be parsed. The
-// iterator takes ownership of the payload.
-func MakeIPv6PayloadIterator(nextHdrIdentifier IPv6ExtensionHeaderIdentifier, payload buffer.Buffer) IPv6PayloadIterator {
-	return IPv6PayloadIterator{
-		nextHdrIdentifier: nextHdrIdentifier,
-		payload:           payload,
-		nextOffset:        IPv6FixedHeaderSize,
-	}
-}
-
-// Release frees the resources owned by the iterator.
-func (i *IPv6PayloadIterator) Release() {
-	i.payload.Release()
-}
-
-// AsRawHeader returns the remaining payload of i as a raw header and
-// optionally consumes the iterator.
-//
-// If consume is true, calls to Next after calling AsRawHeader on i will
-// indicate that the iterator is done. The returned header takes ownership of
-// its payload.
-func (i *IPv6PayloadIterator) AsRawHeader(consume bool) IPv6RawPayloadHeader {
-	identifier := i.nextHdrIdentifier
-
-	var buf buffer.Buffer
-	if consume {
-		// Since we consume the iterator, we return the payload as is.
-		buf = i.payload
-
-		// Mark i as done, but keep track of where we were for error reporting.
-		*i = IPv6PayloadIterator{
-			nextHdrIdentifier: IPv6NoNextHeaderIdentifier,
-			headerOffset:      i.headerOffset,
-			nextOffset:        i.nextOffset,
-		}
-	} else {
-		buf = i.payload.Clone()
-	}
-
-	return IPv6RawPayloadHeader{Identifier: identifier, Buf: buf}
-}
-
-// Next returns the next item in the payload.
-//
-// If the next item is not a known IPv6 extension header, IPv6RawPayloadHeader
-// will be returned with the remaining bytes and next header identifier.
-//
-// The return is of the format (header, done, error). done will be true when
-// Next is unable to return anything because the iterator has reached the end of
-// the payload, or an error occurred.
-func (i *IPv6PayloadIterator) Next() (IPv6PayloadHeader, bool, error) {
-	i.headerOffset = i.nextOffset
-	i.parseOffset = 0
-	// We could be forced to return i as a raw header when the previous header was
-	// a fragment extension header as the data following the fragment extension
-	// header may not be complete.
-	if i.forceRaw {
-		return i.AsRawHeader(true /* consume */), false, nil
-	}
-
-	// Is the header we are parsing a known extension header?
-	switch i.nextHdrIdentifier {
-	case IPv6HopByHopOptionsExtHdrIdentifier:
-		nextHdrIdentifier, view, err := i.nextHeaderData(false /* fragmentHdr */, nil)
-		if err != nil {
-			return nil, true, err
-		}
-
-		i.nextHdrIdentifier = nextHdrIdentifier
-		return IPv6HopByHopOptionsExtHdr{ipv6OptionsExtHdr{view}}, false, nil
-	case IPv6RoutingExtHdrIdentifier:
-		nextHdrIdentifier, view, err := i.nextHeaderData(false /* fragmentHdr */, nil)
-		if err != nil {
-			return nil, true, err
-		}
-
-		i.nextHdrIdentifier = nextHdrIdentifier
-		return IPv6RoutingExtHdr{view}, false, nil
-	case IPv6FragmentExtHdrIdentifier:
-		var data [6]byte
-		// We ignore the returned bytes because we know the fragment extension
-		// header specific data will fit in data.
-		nextHdrIdentifier, _, err := i.nextHeaderData(true /* fragmentHdr */, data[:])
-		if err != nil {
-			return nil, true, err
-		}
-
-		fragmentExtHdr := IPv6FragmentExtHdr(data)
-
-		// If the packet is not the first fragment, do not attempt to parse anything
-		// after the fragment extension header as the payload following the fragment
-		// extension header should not contain any headers; the first fragment must
-		// hold all the headers up to and including any upper layer headers, as per
-		// RFC 8200 section 4.5.
-		if fragmentExtHdr.FragmentOffset() != 0 {
-			i.forceRaw = true
-		}
-
-		i.nextHdrIdentifier = nextHdrIdentifier
-		return fragmentExtHdr, false, nil
-	case IPv6DestinationOptionsExtHdrIdentifier:
-		nextHdrIdentifier, view, err := i.nextHeaderData(false /* fragmentHdr */, nil)
-		if err != nil {
-			return nil, true, err
-		}
-
-		i.nextHdrIdentifier = nextHdrIdentifier
-		return IPv6DestinationOptionsExtHdr{ipv6OptionsExtHdr{view}}, false, nil
-	case IPv6NoNextHeaderIdentifier:
-		// This indicates the end of the IPv6 payload.
-		return nil, true, nil
-
-	default:
-		// The header we are parsing is not a known extension header. Return the
-		// raw payload.
-		return i.AsRawHeader(true /* consume */), false, nil
-	}
-}
-
-// NextHeaderIdentifier returns the identifier of the header next returned by
-// it.Next().
-func (i *IPv6PayloadIterator) NextHeaderIdentifier() IPv6ExtensionHeaderIdentifier {
-	return i.nextHdrIdentifier
-}
-
-// nextHeaderData returns the extension header's Next Header field and raw data.
-//
-// fragmentHdr indicates that the extension header being parsed is the Fragment
-// extension header so the Length field should be ignored as it is Reserved
-// for the Fragment extension header.
-//
-// If bytes is not nil, extension header specific data will be read into bytes
-// if it has enough capacity. If bytes is provided but does not have enough
-// capacity for the data, nextHeaderData will panic.
-func (i *IPv6PayloadIterator) nextHeaderData(fragmentHdr bool, bytes []byte) (IPv6ExtensionHeaderIdentifier, *buffer.View, error) {
-	// We ignore the number of bytes read because we know we will only ever read
-	// at max 1 bytes since rune has a length of 1. If we read 0 bytes, the Read
-	// would return io.EOF to indicate that io.Reader has reached the end of the
-	// payload.
-	rdr := i.payload.AsBufferReader()
-	nextHdrIdentifier, err := rdr.ReadByte()
-	if err != nil {
-		return 0, nil, fmt.Errorf("error when reading the Next Header field for extension header with id = %d: %w", i.nextHdrIdentifier, err)
-	}
-	i.parseOffset++
-
-	var length uint8
-	length, err = rdr.ReadByte()
-	if err != nil {
-		if fragmentHdr {
-			return 0, nil, fmt.Errorf("error when reading the Length field for extension header with id = %d: %w", i.nextHdrIdentifier, err)
-		}
-
-		return 0, nil, fmt.Errorf("error when reading the Reserved field for extension header with id = %d: %w", i.nextHdrIdentifier, err)
-	}
-	if fragmentHdr {
-		length = 0
-	}
-
-	// Make parseOffset point to the first byte of the Extension Header
-	// specific data.
-	i.parseOffset++
-
-	// length is in 8 byte chunks but doesn't include the first one.
-	// See RFC 8200 for each header type, sections 4.3-4.6 and the requirement
-	// in section 4.8 for new extension headers at the top of page 24.
-	//   [ Hdr Ext Len ] ... Length of the Destination Options header in 8-octet
-	//   units, not including the first 8 octets.
-	i.nextOffset += uint32((length + 1) * ipv6ExtHdrLenBytesPerUnit)
-
-	bytesLen := int(length)*ipv6ExtHdrLenBytesPerUnit + ipv6ExtHdrLenBytesExcluded
-	if fragmentHdr {
-		if n := len(bytes); n < bytesLen {
-			panic(fmt.Sprintf("bytes only has space for %d bytes but need space for %d bytes (length = %d) for extension header with id = %d", n, bytesLen, length, i.nextHdrIdentifier))
-		}
-		if n, err := io.ReadFull(&rdr, bytes); err != nil {
-			return 0, nil, fmt.Errorf("read %d out of %d extension header data bytes (length = %d) for header with id = %d: %w", n, bytesLen, length, i.nextHdrIdentifier, err)
-		}
-		return IPv6ExtensionHeaderIdentifier(nextHdrIdentifier), nil, nil
-	}
-	v := buffer.NewView(bytesLen)
-	if n, err := io.CopyN(v, &rdr, int64(bytesLen)); err != nil {
-		if err == io.EOF {
-			err = io.ErrUnexpectedEOF
-		}
-		v.Release()
-		return 0, nil, fmt.Errorf("read %d out of %d extension header data bytes (length = %d) for header with id = %d: %w", n, bytesLen, length, i.nextHdrIdentifier, err)
-	}
-	return IPv6ExtensionHeaderIdentifier(nextHdrIdentifier), v, nil
-}
-
 // IPv6SerializableExtHdr provides serialization for IPv6 extension
 // headers.
 type IPv6SerializableExtHdr interface {
diff --git a/monitor_android.go b/monitor_android.go
index 2734c85..1c7e711 100644
--- a/monitor_android.go
+++ b/monitor_android.go
@@ -51,12 +51,11 @@ func (m *defaultInterfaceMonitor) checkUpdate() error {
 		return err
 	}
 
-	oldInterface := m.defaultInterface.Load()
 	newInterface, err := m.interfaceFinder.ByIndex(link.Attrs().Index)
 	if err != nil {
 		return E.Cause(err, "find updated interface: ", link.Attrs().Name)
 	}
-	m.defaultInterface.Store(newInterface)
+	oldInterface := m.defaultInterface.Swap(newInterface)
 	if oldInterface != nil && oldInterface.Equals(*newInterface) && oldVPNEnabled == m.androidVPNEnabled {
 		return nil
 	}
diff --git a/monitor_darwin.go b/monitor_darwin.go
index 88ea90c..f937c37 100644
--- a/monitor_darwin.go
+++ b/monitor_darwin.go
@@ -165,12 +165,11 @@ func (m *defaultInterfaceMonitor) checkUpdate() error {
 	if defaultInterface == nil {
 		return ErrNoRoute
 	}
-	oldInterface := m.defaultInterface.Load()
 	newInterface, err := m.interfaceFinder.ByIndex(defaultInterface.Index)
 	if err != nil {
 		return E.Cause(err, "find updated interface: ", defaultInterface.Name)
 	}
-	m.defaultInterface.Store(newInterface)
+	oldInterface := m.defaultInterface.Swap(newInterface)
 	if oldInterface != nil && oldInterface.Equals(*newInterface) {
 		return nil
 	}
diff --git a/monitor_linux.go b/monitor_linux.go
index e92f469..86dd28b 100644
--- a/monitor_linux.go
+++ b/monitor_linux.go
@@ -27,7 +27,7 @@ type networkUpdateMonitor struct {
 var ErrNetlinkBanned = E.New(
 	"netlink socket in Android is banned by Google, " +
 		"use the root or system (ADB) user to run sing-box, " +
-		"or switch to the sing-box Adnroid graphical interface client",
+		"or switch to the sing-box Android graphical interface client",
 )
 
 func NewNetworkUpdateMonitor(logger logger.Logger) (NetworkUpdateMonitor, error) {
diff --git a/monitor_linux_default.go b/monitor_linux_default.go
index e9cce1d..72ba1be 100644
--- a/monitor_linux_default.go
+++ b/monitor_linux_default.go
@@ -25,12 +25,11 @@ func (m *defaultInterfaceMonitor) checkUpdate() error {
 			return err
 		}
 
-		oldInterface := m.defaultInterface.Load()
 		newInterface, err := m.interfaceFinder.ByIndex(link.Attrs().Index)
 		if err != nil {
 			return E.Cause(err, "find updated interface: ", link.Attrs().Name)
 		}
-		m.defaultInterface.Store(newInterface)
+		oldInterface := m.defaultInterface.Swap(newInterface)
 		if oldInterface != nil && oldInterface.Equals(*newInterface) {
 			return nil
 		}
diff --git a/monitor_windows.go b/monitor_windows.go
index 179f074..18a795f 100644
--- a/monitor_windows.go
+++ b/monitor_windows.go
@@ -102,12 +102,11 @@ func (m *defaultInterfaceMonitor) checkUpdate() error {
 		return ErrNoRoute
 	}
 
-	oldInterface := m.defaultInterface.Load()
 	newInterface, err := m.interfaceFinder.ByIndex(index)
 	if err != nil {
 		return E.Cause(err, "find updated interface: ", alias)
 	}
-	m.defaultInterface.Store(newInterface)
+	oldInterface := m.defaultInterface.Swap(newInterface)
 	if oldInterface != nil && oldInterface.Equals(*newInterface) {
 		return nil
 	}
diff --git a/tun_darwin.go b/tun_darwin.go
index e887ce8..a0dd54a 100644
--- a/tun_darwin.go
+++ b/tun_darwin.go
@@ -268,45 +268,47 @@ func (t *NativeTun) UpdateRouteOptions(tunOptions Options) error {
 }
 
 func (t *NativeTun) setRoutes() error {
-	if t.options.AutoRoute && t.options.FileDescriptor == 0 {
+	if t.options.FileDescriptor == 0 {
 		routeRanges, err := t.options.BuildAutoRouteRanges(false)
 		if err != nil {
 			return err
 		}
-		gateway4, gateway6 := t.options.Inet4GatewayAddr(), t.options.Inet6GatewayAddr()
-		for _, destination := range routeRanges {
-			var gateway netip.Addr
-			if destination.Addr().Is4() {
-				gateway = gateway4
-			} else {
-				gateway = gateway6
-			}
-			var interfaceIndex int
-			if t.options.InterfaceScope {
-				iff, err := t.options.InterfaceFinder.ByName(t.options.Name)
-				if err != nil {
-					return err
-				}
-				interfaceIndex = iff.Index
-			}
-			err = execRoute(unix.RTM_ADD, t.options.InterfaceScope, interfaceIndex, destination, gateway)
-			if err != nil {
-				if errors.Is(err, unix.EEXIST) {
-					err = execRoute(unix.RTM_DELETE, false, 0, destination, gateway)
-					if err != nil {
-						return E.Cause(err, "remove existing route: ", destination)
-					}
-					err = execRoute(unix.RTM_ADD, t.options.InterfaceScope, interfaceIndex, destination, gateway)
-					if err != nil {
-						return E.Cause(err, "re-add route: ", destination)
-					}
+		if len(routeRanges) > 0 {
+			gateway4, gateway6 := t.options.Inet4GatewayAddr(), t.options.Inet6GatewayAddr()
+			for _, destination := range routeRanges {
+				var gateway netip.Addr
+				if destination.Addr().Is4() {
+					gateway = gateway4
 				} else {
-					return E.Cause(err, "add route: ", destination)
+					gateway = gateway6
+				}
+				var interfaceIndex int
+				if t.options.InterfaceScope {
+					iff, err := t.options.InterfaceFinder.ByName(t.options.Name)
+					if err != nil {
+						return err
+					}
+					interfaceIndex = iff.Index
+				}
+				err = execRoute(unix.RTM_ADD, t.options.InterfaceScope, interfaceIndex, destination, gateway)
+				if err != nil {
+					if errors.Is(err, unix.EEXIST) {
+						err = execRoute(unix.RTM_DELETE, false, 0, destination, gateway)
+						if err != nil {
+							return E.Cause(err, "remove existing route: ", destination)
+						}
+						err = execRoute(unix.RTM_ADD, t.options.InterfaceScope, interfaceIndex, destination, gateway)
+						if err != nil {
+							return E.Cause(err, "re-add route: ", destination)
+						}
+					} else {
+						return E.Cause(err, "add route: ", destination)
+					}
 				}
 			}
+			flushDNSCache()
+			t.routeSet = true
 		}
-		flushDNSCache()
-		t.routeSet = true
 	}
 	return nil
 }
diff --git a/tun_linux.go b/tun_linux.go
index 8c7bac6..72aac6a 100644
--- a/tun_linux.go
+++ b/tun_linux.go
@@ -202,7 +202,6 @@ func (t *NativeTun) enableGSO() error {
 	err = setUDPOffload(t.tunFd)
 	if err != nil {
 		t.gro.disableUDPGRO()
-		return E.Cause(err, "enable UDP offload")
 	}
 	return nil
 }
diff --git a/tun_rules.go b/tun_rules.go
index 93b0430..c1b983f 100644
--- a/tun_rules.go
+++ b/tun_rules.go
@@ -108,7 +108,7 @@ const autoRouteUseSubRanges = runtime.GOOS == "darwin"
 
 func (o *Options) BuildAutoRouteRanges(underNetworkExtension bool) ([]netip.Prefix, error) {
 	var routeRanges []netip.Prefix
-	if o.AutoRoute && len(o.Inet4Address) > 0 {
+	if len(o.Inet4Address) > 0 {
 		var inet4Ranges []netip.Prefix
 		if len(o.Inet4RouteAddress) > 0 {
 			inet4Ranges = o.Inet4RouteAddress
@@ -119,19 +119,27 @@ func (o *Options) BuildAutoRouteRanges(underNetworkExtension bool) ([]netip.Pref
 					}
 				}
 			}
-		} else if autoRouteUseSubRanges && !underNetworkExtension {
-			inet4Ranges = []netip.Prefix{
-				netip.PrefixFrom(netip.AddrFrom4([4]byte{0: 1}), 8),
-				netip.PrefixFrom(netip.AddrFrom4([4]byte{0: 2}), 7),
-				netip.PrefixFrom(netip.AddrFrom4([4]byte{0: 4}), 6),
-				netip.PrefixFrom(netip.AddrFrom4([4]byte{0: 8}), 5),
-				netip.PrefixFrom(netip.AddrFrom4([4]byte{0: 16}), 4),
-				netip.PrefixFrom(netip.AddrFrom4([4]byte{0: 32}), 3),
-				netip.PrefixFrom(netip.AddrFrom4([4]byte{0: 64}), 2),
-				netip.PrefixFrom(netip.AddrFrom4([4]byte{0: 128}), 1),
+		} else if o.AutoRoute {
+			if autoRouteUseSubRanges && !underNetworkExtension {
+				inet4Ranges = []netip.Prefix{
+					netip.PrefixFrom(netip.AddrFrom4([4]byte{0: 1}), 8),
+					netip.PrefixFrom(netip.AddrFrom4([4]byte{0: 2}), 7),
+					netip.PrefixFrom(netip.AddrFrom4([4]byte{0: 4}), 6),
+					netip.PrefixFrom(netip.AddrFrom4([4]byte{0: 8}), 5),
+					netip.PrefixFrom(netip.AddrFrom4([4]byte{0: 16}), 4),
+					netip.PrefixFrom(netip.AddrFrom4([4]byte{0: 32}), 3),
+					netip.PrefixFrom(netip.AddrFrom4([4]byte{0: 64}), 2),
+					netip.PrefixFrom(netip.AddrFrom4([4]byte{0: 128}), 1),
+				}
+			} else {
+				inet4Ranges = []netip.Prefix{netip.PrefixFrom(netip.IPv4Unspecified(), 0)}
+			}
+		} else if runtime.GOOS == "darwin" {
+			for _, address := range o.Inet4Address {
+				if address.Bits() < 32 {
+					inet4Ranges = append(inet4Ranges, address.Masked())
+				}
 			}
-		} else {
-			inet4Ranges = []netip.Prefix{netip.PrefixFrom(netip.IPv4Unspecified(), 0)}
 		}
 		if len(o.Inet4RouteExcludeAddress) == 0 {
 			routeRanges = append(routeRanges, inet4Ranges...)
@@ -161,19 +169,27 @@ func (o *Options) BuildAutoRouteRanges(underNetworkExtension bool) ([]netip.Pref
 					}
 				}
 			}
-		} else if autoRouteUseSubRanges && !underNetworkExtension {
-			inet6Ranges = []netip.Prefix{
-				netip.PrefixFrom(netip.AddrFrom16([16]byte{0: 1}), 8),
-				netip.PrefixFrom(netip.AddrFrom16([16]byte{0: 2}), 7),
-				netip.PrefixFrom(netip.AddrFrom16([16]byte{0: 4}), 6),
-				netip.PrefixFrom(netip.AddrFrom16([16]byte{0: 8}), 5),
-				netip.PrefixFrom(netip.AddrFrom16([16]byte{0: 16}), 4),
-				netip.PrefixFrom(netip.AddrFrom16([16]byte{0: 32}), 3),
-				netip.PrefixFrom(netip.AddrFrom16([16]byte{0: 64}), 2),
-				netip.PrefixFrom(netip.AddrFrom16([16]byte{0: 128}), 1),
+		} else if o.AutoRoute {
+			if autoRouteUseSubRanges && !underNetworkExtension {
+				inet6Ranges = []netip.Prefix{
+					netip.PrefixFrom(netip.AddrFrom16([16]byte{0: 1}), 8),
+					netip.PrefixFrom(netip.AddrFrom16([16]byte{0: 2}), 7),
+					netip.PrefixFrom(netip.AddrFrom16([16]byte{0: 4}), 6),
+					netip.PrefixFrom(netip.AddrFrom16([16]byte{0: 8}), 5),
+					netip.PrefixFrom(netip.AddrFrom16([16]byte{0: 16}), 4),
+					netip.PrefixFrom(netip.AddrFrom16([16]byte{0: 32}), 3),
+					netip.PrefixFrom(netip.AddrFrom16([16]byte{0: 64}), 2),
+					netip.PrefixFrom(netip.AddrFrom16([16]byte{0: 128}), 1),
+				}
+			} else {
+				inet6Ranges = []netip.Prefix{netip.PrefixFrom(netip.IPv6Unspecified(), 0)}
+			}
+		} else if runtime.GOOS == "darwin" {
+			for _, address := range o.Inet6Address {
+				if address.Bits() < 32 {
+					inet6Ranges = append(inet6Ranges, address.Masked())
+				}
 			}
-		} else {
-			inet6Ranges = []netip.Prefix{netip.PrefixFrom(netip.IPv6Unspecified(), 0)}
 		}
 		if len(o.Inet6RouteExcludeAddress) == 0 {
 			routeRanges = append(routeRanges, inet6Ranges...)