Me and my wife figured out some kind of workaround for the splitscreen blackout disconnecting issue... First Blackout game always works (for us). But after that it’s always disconnecting us early in the game.
What we did was:
Play the first game. Then play a match mp (we played hardcore domination), then back to blackout. Worked all evening for us 👍
So one game blackout, one game mp, one game blackout and so on.