TMG 2010 Loss Internet Connection

Hi

I have TMG 2010 SP2 on Windows Server 2008 r2 Server.

Recently we are experementing problems with internet connection on client computers. The issue is that After several hours or several days of server is up. The clients loss internet connection and the temporal solution is restart server.

TMG server not freeze and is possible access from RDP and response Ping. I check communication to ISP and Internal LAN and communication not loss.

Any suggestion for this issue?

thanks.