Stuck on connecting screen

Hi there,

My friend and I were attempting to join a custom game together but we keep getting stuck on 'connecting' and are unable to get into each other's lobby. I believe it may be an issue with my friend's setup as I can join all other lobbies but they cannot (they're using a 4g wireless modem as they can't get regular internet where they live).

I've got them to disable IPv6 via the control panel as was suggested in other posts but it didn't seem to help. I also had the ICE adaptor debugger open and whenever my friend joined it would seem to get stuck on 'awaitingCandidates' and then disconnect.

What is weird is that it will work with no issues about 5% of the time and we can play through a full game.

Was wondering if anyone had experienced similar issues or had any solutions.