Lan Connection Issues

For some odd reason, everytime my brother and I play a lan game it seems to disconnect after 30-45 minutes into the game.  Something along the lines of 'Player has Left the game'.

We use a wireless lan system, My pc goes wireless (connection is either 3 or 4 bars of strenght [good -> very good]), where as my brother is a direct line in, into the router.

Both our PC's surpass the recommended specs of this game so im somewhat at a loss as to what is causing this...

Please Help!

Thank You