Multiplayer lan issue- disconnecting

When me and my brother try to play a lan game of Sins of a Solar Empire it will work fine for 30 minutes to two hours upon which time it shows both of us that the other has disconnected (i.e. i think he has disconnected and he thinks i have disconnected). The time taken for this to occur varies but it is much more likely after loading a saved game.

This problem only effects me in LAN games (i can play internet and solo games fine), are there any fixes?