about Isa Server

I have  the wireless router,The ip adress of Wireless router is192.168.5.230InIsa server 2006this ip adress have given full access for internet.inWirelessRouter configured the DHCP as192.168.10.10-192.168.10.199.There are 10or more  clients connected to Wireless router.But sometimes the Isa server blocks the internet connection (this ip adress 192.168.5.230)for router.  blocking time 10 minutes or more.What's problem i don't know. I  tried all variants of "flood migrations confugiration".NoResult!!Please help