Playing via Hamachi.

Hello everyone! We've tried different versions of Hamachi, different versions of the game, and different Hamachi settings – the result is always the same: we create a network, connect, and start playing, everything works fine! Then one player disconnects, almost immediately... this happens very often during a player's battle, mostly even in the first turn. We don't know what to do...
P.S. Maybe it's his Windows 7?