Originally Posted by
Saab Dastard
My suggestion, to eliminate some variables, would be to switch DHCP for your local LAN off on the router. Set your PCs IP configuration manually, including DNS servers. The DNS servers you set on your PCs should be the ISP's DNS or an external internet DNS server.
You wouldn't need to turn off DHCP in that instance, as the action of configuring an IP address on the PC stops it from broadcasting for an address via DHCP (and it's one less step to misconfigure on the router).