Absolutely unplayable over LAN

I’ve been trying to play this game with my wife (the entire reason we bought it), and we simply cannot play the game due to disconnections. Literally within 20 seconds of getting into the game, I get the connection lost icon, and I get booted. I’ve forwarded ports for her and then for me, neither works.

We’ve tried connecting over the roster and LAN. Roster disconnects after a short period of time, and nothing ever shows up when we try to use LAN.

Is there a known fix to this?