I think I my have found a bug with the DIR-850L. Whenever I go to Settings, Internet, Advanced Settings then set the Primary DNS Server to my internal Windows 2008 Server, it blocks access to the router & Internet from that server. All other clients can access the Internet and the server itself. If I change the IP address of the Windows server, I can browse the internet fine. I should be able to use my own DNS server for my internal clients.