if no dns param then use whatever pipe chose

server.go

@@ -28,7 +28,10 @@ func NewServer(c *Config) *Server {
 		PreferGo: true,
 		Dial: func(ctx context.Context, network, addr string) (net.Conn, error) {
 			d := net.Dialer{Timeout: c.Timeout}
-			return d.DialContext(ctx, network, c.DNS)
+			if c.DNS != "" {
+				addr = c.DNS
+			}
+			return d.DialContext(ctx, network, addr)
 		},
 	}
 	transport := &http.Transport{}