Question about MTU

[HirbodBehnam]

Hello Thanks for the project! I do have a small question about MTU. My MTU values are like this:

• Server Internet: 1500
• Home Internet: 1500
• Server's Wireguard Interface: 1420
• Both swgp-go's: 1500 With this setup, Wireguard connects to internet however, I get this warning on my client's swgp-go and the speed is terrible:

  2022-11-18T07:44:34.763+0330 WARN service/client.go:353 Failed to write swgpPacket to proxyConn {"client": "client", "wgListen": "127.0.0.1:20222", "clientAddress": "127.0.0.1:54883", "proxyAddress": "X.X.X.X:Y", "error": "write udp [::]:55084->X.X.X.X:Y: wsasendto: A message sent on a datagram socket was larger than the internal message buffer or some other network limit, or the buffer used to receive a datagram into was smaller than the datagram itself."}

  Server acknowledges the new UDP session and there is no log afterwards.

My server is Ubuntu 22 and my PC is Windows 10. I also use the zero overhead mode.

I'd be glad if you could help me. Thanks

[database64128]

Are you sure your home Internet's MTU is 1500? Some residential ISPs use PPPoE for authentication, which reduces the effective MTU to 1492.

[HirbodBehnam]

Maybe I tried reducing swgp-go's (client and server) MTU to 1492 and this time there are logs both in my server and client.

2022-11-18T08:59:13.871Z WARN service/server_linux.go:608 Packet from wgConn discarded {"server": "server", "proxyListen": ":Y", "clientAddress": "[X]:20086", "wgAddress": "127.0.0.1:Y", "packetLength": 1430, "error": "the packet is larger than the supplied buffer"}

Should I reduce my server's MTU as well?

[database64128]

Yes, you also need to lower your wg tunnel's MTU to 1408.

[HirbodBehnam]

Thanks!