Sorry I was travelling.

I just tried Setting TorGuard Wireguard using smartphone app and configure it on AX1800 3.207 firmware.

My wifi works as expected. Pls note I did a clear upgrade to 3.207.

So maybe your settings was messed up for some reason. Can you do a firmware reset and try again?

I thought it could be a MTU setting problem but as you have normal Internet on cable, this should not be the case.