diff --git a/common/dialer/default.go b/common/dialer/default.go
index 992b3a89b..f3481439b 100644
--- a/common/dialer/default.go
+++ b/common/dialer/default.go
@@ -20,6 +20,8 @@ import (
 	M "github.com/sagernet/sing/common/metadata"
 	N "github.com/sagernet/sing/common/network"
 	"github.com/sagernet/sing/service"
+
+	"github.com/metacubex/tfo-go"
 )
 
 var (
@@ -28,8 +30,8 @@ var (
 )
 
 type DefaultDialer struct {
-	dialer4                tcpDialer
-	dialer6                tcpDialer
+	dialer4                tfo.Dialer
+	dialer6                tfo.Dialer
 	udpDialer4             net.Dialer
 	udpDialer6             net.Dialer
 	udpListener            net.ListenConfig
@@ -177,19 +179,10 @@ func NewDefault(ctx context.Context, options option.DialerOptions) (*DefaultDial
 		udpAddr6 = M.SocksaddrFrom(bindAddr, 0).String()
 	}
 	if options.TCPMultiPath {
-		if !go121Available {
-			return nil, E.New("MultiPath TCP requires go1.21, please recompile your binary.")
-		}
-		setMultiPathTCP(&dialer4)
-	}
-	tcpDialer4, err := newTCPDialer(dialer4, options.TCPFastOpen)
-	if err != nil {
-		return nil, err
-	}
-	tcpDialer6, err := newTCPDialer(dialer6, options.TCPFastOpen)
-	if err != nil {
-		return nil, err
+		dialer4.SetMultipathTCP(true)
 	}
+	tcpDialer4 := tfo.Dialer{Dialer: dialer4, DisableTFO: !options.TCPFastOpen}
+	tcpDialer6 := tfo.Dialer{Dialer: dialer6, DisableTFO: !options.TCPFastOpen}
 	return &DefaultDialer{
 		dialer4:                tcpDialer4,
 		dialer6:                tcpDialer6,
@@ -269,7 +262,7 @@ func (d *DefaultDialer) DialParallelInterface(ctx context.Context, network strin
 	}
 	var dialer net.Dialer
 	if N.NetworkName(network) == N.NetworkTCP {
-		dialer = dialerFromTCPDialer(d.dialer4)
+		dialer = d.dialer4.Dialer
 	} else {
 		dialer = d.udpDialer4
 	}
@@ -317,9 +310,9 @@ func (d *DefaultDialer) ListenPacket(ctx context.Context, destination M.Socksadd
 
 func (d *DefaultDialer) DialerForICMPDestination(destination netip.Addr) net.Dialer {
 	if !destination.Is6() {
-		return dialerFromTCPDialer(d.dialer6)
+		return d.dialer6.Dialer
 	} else {
-		return dialerFromTCPDialer(d.dialer4)
+		return d.dialer4.Dialer
 	}
 }
 
diff --git a/common/dialer/default_go1.20.go b/common/dialer/default_go1.20.go
deleted file mode 100644
index 9dde955f8..000000000
--- a/common/dialer/default_go1.20.go
+++ /dev/null
@@ -1,19 +0,0 @@
-//go:build go1.20
-
-package dialer
-
-import (
-	"net"
-
-	"github.com/metacubex/tfo-go"
-)
-
-type tcpDialer = tfo.Dialer
-
-func newTCPDialer(dialer net.Dialer, tfoEnabled bool) (tcpDialer, error) {
-	return tfo.Dialer{Dialer: dialer, DisableTFO: !tfoEnabled}, nil
-}
-
-func dialerFromTCPDialer(dialer tcpDialer) net.Dialer {
-	return dialer.Dialer
-}
diff --git a/common/dialer/default_go1.21.go b/common/dialer/default_go1.21.go
deleted file mode 100644
index 6ecb5b257..000000000
--- a/common/dialer/default_go1.21.go
+++ /dev/null
@@ -1,11 +0,0 @@
-//go:build go1.21
-
-package dialer
-
-import "net"
-
-const go121Available = true
-
-func setMultiPathTCP(dialer *net.Dialer) {
-	dialer.SetMultipathTCP(true)
-}
diff --git a/common/dialer/default_nongo1.20.go b/common/dialer/default_nongo1.20.go
deleted file mode 100644
index b2e4638d1..000000000
--- a/common/dialer/default_nongo1.20.go
+++ /dev/null
@@ -1,22 +0,0 @@
-//go:build !go1.20
-
-package dialer
-
-import (
-	"net"
-
-	E "github.com/sagernet/sing/common/exceptions"
-)
-
-type tcpDialer = net.Dialer
-
-func newTCPDialer(dialer net.Dialer, tfoEnabled bool) (tcpDialer, error) {
-	if tfoEnabled {
-		return dialer, E.New("TCP Fast Open requires go1.20, please recompile your binary.")
-	}
-	return dialer, nil
-}
-
-func dialerFromTCPDialer(dialer tcpDialer) net.Dialer {
-	return dialer
-}
diff --git a/common/dialer/default_nongo1.21.go b/common/dialer/default_nongo1.21.go
deleted file mode 100644
index 386d50dd0..000000000
--- a/common/dialer/default_nongo1.21.go
+++ /dev/null
@@ -1,12 +0,0 @@
-//go:build !go1.21
-
-package dialer
-
-import (
-	"net"
-)
-
-const go121Available = false
-
-func setMultiPathTCP(dialer *net.Dialer) {
-}
diff --git a/common/dialer/tfo.go b/common/dialer/tfo.go
index 4832c12da..ae04e71ff 100644
--- a/common/dialer/tfo.go
+++ b/common/dialer/tfo.go
@@ -1,5 +1,3 @@
-//go:build go1.20
-
 package dialer
 
 import (
@@ -32,7 +30,7 @@ type slowOpenConn struct {
 	err         error
 }
 
-func DialSlowContext(dialer *tcpDialer, ctx context.Context, network string, destination M.Socksaddr) (net.Conn, error) {
+func DialSlowContext(dialer *tfo.Dialer, ctx context.Context, network string, destination M.Socksaddr) (net.Conn, error) {
 	if dialer.DisableTFO || N.NetworkName(network) != N.NetworkTCP {
 		switch N.NetworkName(network) {
 		case N.NetworkTCP, N.NetworkUDP:
diff --git a/common/dialer/tfo_stub.go b/common/dialer/tfo_stub.go
deleted file mode 100644
index 144902e5b..000000000
--- a/common/dialer/tfo_stub.go
+++ /dev/null
@@ -1,20 +0,0 @@
-//go:build !go1.20
-
-package dialer
-
-import (
-	"context"
-	"net"
-
-	M "github.com/sagernet/sing/common/metadata"
-	N "github.com/sagernet/sing/common/network"
-)
-
-func DialSlowContext(dialer *tcpDialer, ctx context.Context, network string, destination M.Socksaddr) (net.Conn, error) {
-	switch N.NetworkName(network) {
-	case N.NetworkTCP, N.NetworkUDP:
-		return dialer.DialContext(ctx, network, destination.String())
-	default:
-		return dialer.DialContext(ctx, network, destination.AddrString())
-	}
-}
diff --git a/common/listener/listener_go121.go b/common/listener/listener_go121.go
deleted file mode 100644
index 5af1b05a3..000000000
--- a/common/listener/listener_go121.go
+++ /dev/null
@@ -1,11 +0,0 @@
-//go:build go1.21
-
-package listener
-
-import "net"
-
-const go121Available = true
-
-func setMultiPathTCP(listenConfig *net.ListenConfig) {
-	listenConfig.SetMultipathTCP(true)
-}
diff --git a/common/listener/listener_go123.go b/common/listener/listener_go123.go
deleted file mode 100644
index 2e1f4cf43..000000000
--- a/common/listener/listener_go123.go
+++ /dev/null
@@ -1,16 +0,0 @@
-//go:build go1.23
-
-package listener
-
-import (
-	"net"
-	"time"
-)
-
-func setKeepAliveConfig(listener *net.ListenConfig, idle time.Duration, interval time.Duration) {
-	listener.KeepAliveConfig = net.KeepAliveConfig{
-		Enable:   true,
-		Idle:     idle,
-		Interval: interval,
-	}
-}
diff --git a/common/listener/listener_nongo121.go b/common/listener/listener_nongo121.go
deleted file mode 100644
index 36073afe3..000000000
--- a/common/listener/listener_nongo121.go
+++ /dev/null
@@ -1,10 +0,0 @@
-//go:build !go1.21
-
-package listener
-
-import "net"
-
-const go121Available = false
-
-func setMultiPathTCP(listenConfig *net.ListenConfig) {
-}
diff --git a/common/listener/listener_nongo123.go b/common/listener/listener_nongo123.go
deleted file mode 100644
index e1582981c..000000000
--- a/common/listener/listener_nongo123.go
+++ /dev/null
@@ -1,15 +0,0 @@
-//go:build !go1.23
-
-package listener
-
-import (
-	"net"
-	"time"
-
-	"github.com/sagernet/sing/common/control"
-)
-
-func setKeepAliveConfig(listener *net.ListenConfig, idle time.Duration, interval time.Duration) {
-	listener.KeepAlive = idle
-	listener.Control = control.Append(listener.Control, control.SetKeepAlivePeriod(idle, interval))
-}
diff --git a/common/listener/listener_tcp.go b/common/listener/listener_tcp.go
index 53d7bc86d..7ac7bbba9 100644
--- a/common/listener/listener_tcp.go
+++ b/common/listener/listener_tcp.go
@@ -46,13 +46,14 @@ func (l *Listener) ListenTCP() (net.Listener, error) {
 		if keepInterval == 0 {
 			keepInterval = C.TCPKeepAliveInterval
 		}
-		setKeepAliveConfig(&listenConfig, keepIdle, keepInterval)
+		listenConfig.KeepAliveConfig = net.KeepAliveConfig{
+			Enable:   true,
+			Idle:     keepIdle,
+			Interval: keepInterval,
+		}
 	}
 	if l.listenOptions.TCPMultiPath {
-		if !go121Available {
-			return nil, E.New("MultiPath TCP requires go1.21, please recompile your binary.")
-		}
-		setMultiPathTCP(&listenConfig)
+		listenConfig.SetMultipathTCP(true)
 	}
 	if l.tproxy {
 		listenConfig.Control = control.Append(listenConfig.Control, func(network, address string, conn syscall.RawConn) error {
diff --git a/common/tls/ech_stub.go b/common/tls/ech_stub.go
deleted file mode 100644
index 357466c07..000000000
--- a/common/tls/ech_stub.go
+++ /dev/null
@@ -1,23 +0,0 @@
-//go:build !go1.24
-
-package tls
-
-import (
-	"context"
-	"crypto/tls"
-
-	"github.com/sagernet/sing-box/option"
-	E "github.com/sagernet/sing/common/exceptions"
-)
-
-func parseECHClientConfig(ctx context.Context, clientConfig ECHCapableConfig, options option.OutboundTLSOptions) (Config, error) {
-	return nil, E.New("ECH requires go1.24, please recompile your binary.")
-}
-
-func parseECHServerConfig(ctx context.Context, options option.InboundTLSOptions, tlsConfig *tls.Config, echKeyPath *string) error {
-	return E.New("ECH requires go1.24, please recompile your binary.")
-}
-
-func (c *STDServerConfig) setECHServerConfig(echKey []byte) error {
-	panic("unreachable")
-}