I've found it is possible to join games by lowering graphics settings. I cant say what exactly needs to be lowered for it to work, because it seems slightly random. However with low settings I can join games fine. It is not playable, however: I just get stuck rooted to the spot unable to do anything except look around. There is also an issue with other players not being animated smoothly and seemingly not moving around except in 'stages', jumping from place to place with a delay of a second or so and without any model animation in the meantime.