diff --git a/tun.go b/tun.go
index 6d86228..e08a60b 100644
--- a/tun.go
+++ b/tun.go
@@ -85,7 +85,7 @@ func CalculateInterfaceName(name string) (tunName string) {
 	for _, netInterface := range interfaces {
 		if strings.HasPrefix(netInterface.Name, tunName) {
 			index, parseErr := strconv.ParseInt(netInterface.Name[len(tunName):], 10, 16)
-			if parseErr == nil {
+			if parseErr == nil && int(index) >= tunIndex {
 				tunIndex = int(index) + 1
 			}
 		}
diff --git a/tun_rules.go b/tun_rules.go
index 37dcd98..ce5ab31 100644
--- a/tun_rules.go
+++ b/tun_rules.go
@@ -109,6 +109,11 @@ func (o *Options) BuildAutoRouteRanges(underNetworkExtension bool) ([]netip.Pref
 		var inet4Ranges []netip.Prefix
 		if len(o.Inet4RouteAddress) > 0 {
 			inet4Ranges = o.Inet4RouteAddress
+			for _, address := range o.Inet4Address {
+				if address.Bits() < 32 {
+					inet4Ranges = append(inet4Ranges, netipx.RangeOfPrefix(address).Prefixes()...)
+				}
+			}
 		} else if autoRouteUseSubRanges && !underNetworkExtension {
 			inet4Ranges = []netip.Prefix{
 				netip.PrefixFrom(netip.AddrFrom4([4]byte{0: 1}), 8),
@@ -144,6 +149,11 @@ func (o *Options) BuildAutoRouteRanges(underNetworkExtension bool) ([]netip.Pref
 		var inet6Ranges []netip.Prefix
 		if len(o.Inet6RouteAddress) > 0 {
 			inet6Ranges = o.Inet6RouteAddress
+			for _, address := range o.Inet6Address {
+				if address.Bits() < 32 {
+					inet6Ranges = append(inet6Ranges, netipx.RangeOfPrefix(address).Prefixes()...)
+				}
+			}
 		} else if autoRouteUseSubRanges && !underNetworkExtension {
 			inet6Ranges = []netip.Prefix{
 				netip.PrefixFrom(netip.AddrFrom16([16]byte{0: 1}), 8),