Online Multiplayer Connection Issues (Steam PC)

Joining up with a friend through Steam, both on PC. When attempting to play online there are constant errors of connection to each other and “retrieving information.” We are playing together on the same internet connection six feet apart from each other. The person I am in the same game session as is sent into game, while I am not, despite being displayed together in the same game session. He leaves to join with me again and now he is banned from matchmaking after quitting ONE game because he was connected without me due to a game error.

I keep having a similar issue. My roommate and I are on the same connection and one of us always gets booted. Were unable to play together