Well, the game is peer to peer, so if there is any slight drop in your internet, it will cause you to drop out of the game. Unfortunately, there won't be much that 2k will do since you are using mods in the game. I can bet you that they will attribute the instability of your game to the mods.
I'd suggest making sure that you've added the players in the game so that when you disconnect, they can pause for you so that you can try to rejoin.
However, most likely you'll receive and error, "Unable to join Multiplayer session", and the only only fix for that is to reload the saved game or the previous autosave.