http://bugs.winehq.org/show_bug.cgi?id=4445
------- Additional Comments From Andreas.Klauer@metamorpher.de 2006-28-12 12:55 ------- I frequently got those 'Your connection has been interrupted' messages too. Very annoying, because in a TCP/IP game, when a sudden disconnect happens, your character does not get saved properly and you lose some of your progress (quests, items, etc). The situation improved a lot when I reduced X server color depth to 16 bit (less CPU intensive).
However, I doubt this is a wine bug. It's just that for local TCP/IP games, as opposed to Battle.net games, Diablo II does not seem to be able to cope with lag at all. So even slight hangs (which may occur in wine by itself or due to outside processes) cause loss of connection.
There is a solution that works great: Play on Battle.net. Hangs are not a problem there. You can have your Linux box act as a local Battle.net server, see the PVPGN project. All you have to do is install it, run bnetd in default configuration, edit the registry (or use one of the many battlenet gateway selector utilities) to add the server IP to Diablo II list of Battle.net servers, choose 'Open Battle.net', create a game and you're ready to go.
Now you'll notice slight sync problems sometimes, but instead of kicking you out like TCP/IP game does, Diablo II now compensates for what it thinks is caused by Internet lag.
There are also many other advantages over the normal TCP/IP game, since you get the whole Battle.net menu (list of games to select from, easy game creation dialog, host can leave the game without kicking all others out, etc.)
Hope this helps