Every time me and my brother try to play this game at the same time, we get horrible disconnect issues, reaching disconnects of up to 35k at times. It goes away as soon as one of us logs off, but any time we are both logged in to DayZ, it crashes. We've never had problems running any other games at the same time, and frequently play multiplayer games together, while also streaming/downloading many things, so it's likely not our connection.