Hello,
The issue sounds like it could be related to the MTU size.
I’ll ask you to log into the CLI of the device, and run the following commands:
uci set network.[tunnel_name].mtu='1300'
uci commit network
/etc/init.d/network restart
Replace the [tunnel_name] with the name of the WireGuard instance on the RUTX11. After restarting the network, the connection will be lost, but it will recover soon.
Keep in mind, that this MTU only applies to the WireGuard tunnel, if you are experiencing issues even outside the WireGuard tunnel, MTU can be lowered on the mobile interface by navigating to Network → Interfaces → General, editing the mob1s1a1 interface, and in the advanced options setting the Override MTU option to 1300.
Let me know if this helps!
Best regards,