Hi… that’s a bit less information. Do they drop randomly but sometimes play fine? Or can’t they be configured at all? 
If they can’t be configured at all, please try restarting all products or even reseting the Ones and Sub. 
If the ht system works generally but sometimes sub / rears deop, it could be a network issue. In this case I recommend sending a diagnostic directly after the problem occurs and calling Sonos support team. Keep the number of your diagnostic and tell ist support staff.