UNET : RTT on Local Network look high (around 50~60)

Hi everyone, I'm testing the RTT (Round Trip time) in the Local Network with UNET, the results look high, like I said in the topic's title, it get around 50-60ms. The RTT on LAN should be lower than that, maybe around 5~10ms.

My testing code is very simple : the Local client send a message to server and save the current time stamp (sentTime), when local client receive the reply from server, it compare the current time with the sentTime -> got the RTT. Here's the code (very simple)

 float _sentTime;
 void LocalCheckPingViaCmdRpc()
 {
     _sentTime = Time.time;
     CmdServerReceiveCheckingPingRequest();
 }
 
 [Command]
 void CmdServerReceiveCheckingPingRequest()
 {
     RpcClientReceiveCheckingPingMessageFromServer();
 }
 
 [ClientRpc]
 void RpcClientReceiveCheckingPingMessageFromServer()
 {
     if (isLocalPlayer)
     {
         var RTT = (Time.time - _sentTime) * 1000f;
         Debug.LogFormat("Cmd, Rpc -> RTT : {0}", RTT);
     }
 }

You can check out my testing project in Github. I've also tried use NetworkMessage, and switch between Reliable and Unreliable channel but I got the same results.

If the RTT on LocalNetwork got that high, I think when I deploy my game on a dedicated server, it'll got higher, and that not good for some of my real-time multiplayer projects.

Does anyone face the same problem like this before ? Or I've missed some configurations ? Please give me some advices. Thanks so much.