Must restart after checking other app or unlocking device on multiplayer.

When I host a multiplayer game on my Archos 80XS (Android 4.1.1) with a player on an iPod Touch 4, if I check another app or lock my device, when I come back to the app my game works normally a few seconds and then it freezes. Few seconds later, it re-works and re-freezes, etc. I must restart the game to play normally again.