I have closed everything on my computer that uses the internet, but every time I try to join a lobby I get 'Unstable Connection'. I have tried joining about 40 different lobbies now and it's always 'Unstable Connection'. Just now I tried playing a co-op game with my brother who lives 20mins away by train. But every time we try to join one another's lobby, 'Unstable Connection'. It just seems completely impossible to play any multiplayer at all.
I'm curious if anyone else is getting this same error over and over again and if you've found a way to fix it.