I don't know if this has been reported already, so I'm sorry if I'm making a duplicate thread. I've noticed that whenever there's some lag on my internet connection from other people in the house the game seems to freeze up a fair bit then eventually disconnects from the server. It usually starts flickering a few times, slows down a bit, then starts happening more and more frequently until everything stops and I'm back at the main menu with a disconnect message displayed. Other applications are still able to connect and function without issue so I'm led to believe this is a problem with the game.
From what you have described its both an issue with your connection being saturated and the bandwidth requirements for this game. PA still has a bunch of optimization to do in that area. You options are to play with a faster connection, wait for further optimization, or both.
I'm having the same problem but I have a fairly quick connection. I'm even loosing connection during AI matches. Do you know what these may be caused by?