Total War Saga: Troy.
A friend and I bought this game to play a Co-Op Multiplayer campaign together on 11/23/22. Both of us using Steam.
In this instance, I am the host of a multiplayer co-op campaign. I send him the invite code, and when he tries to join me to start the game, he receives a Failed error: "No response from host". Same thing with a direct steam invite to lobby.
When he tries to host the campaign, he gets an Error: "Failed to Host".
So far I have no issues.