diff --git a/adapter/outbound/singmux.go b/adapter/outbound/singmux.go
index 4f3a531c2..b1a64d997 100644
--- a/adapter/outbound/singmux.go
+++ b/adapter/outbound/singmux.go
@@ -81,6 +81,20 @@ func (s *SingMux) ListenPacketContext(ctx context.Context, metadata *C.Metadata,
 	return newPacketConn(pc, s.ProxyAdapter), nil
 }
 
+func (s *SingMux) SupportUDP() bool {
+	if s.onlyTcp {
+		return s.ProxyAdapter.SupportUOT()
+	}
+	return true
+}
+
+func (s *SingMux) SupportUOT() bool {
+	if s.onlyTcp {
+		return s.ProxyAdapter.SupportUOT()
+	}
+	return true
+}
+
 func NewSingMux(option SingMuxOption, proxy C.ProxyAdapter, base ProxyBase) (C.ProxyAdapter, error) {
 	singDialer := &muxSingDialer{dialer: dialer.NewDialer(), proxy: proxy, statistic: option.Statistic}
 	client, err := mux.NewClient(mux.Options{
diff --git a/adapter/outboundgroup/relay.go b/adapter/outboundgroup/relay.go
index a596454f2..ba733616d 100644
--- a/adapter/outboundgroup/relay.go
+++ b/adapter/outboundgroup/relay.go
@@ -92,7 +92,7 @@ func (r *Relay) SupportUDP() bool {
 		switch proxy.SupportWithDialer() {
 		case C.ALLNet:
 		case C.UDP:
-		default: // C.TCP and C.NONet
+		default: // C.TCP and C.InvalidNet
 			return false
 		}
 	}