You issue sounds very similar to mine: Frequent drop to desktop during multiplayer matches - #15 by Thw0rted
I don’t have a solution either. I noticed it seems to happen more often in an “real” online server versus when I’m hosting on LAN, but I’ve had it happen in all sorts of cases, and my daughter actually just had it happen a few minutes ago during a tutorial mission (!). There are logs in the log directory, I attached a few of mine but I never got any useful feedback. (Do the devs even actually monitor these reports?)