I don't used wireless network for filemaker pcs, they are connected by 100Bt wire. No sleep or power saving on, as I said it happens when someone is entering data. No issue with switches (I tested few of them) or routers. I shared the same copy of the database with no records on differentt network (different switch, different OS - Mac Os X, different users) and it still lost communication. It's has to be FileMaker issue.