Imagine if your new web master used port forwarding on the router. The router would/could be the issue.
I have a win 7 machine and a Windows 2008 R2 web server plugged into the same cable router. The win 7 machine has a private IP 10.x.x.x and the web server has a static IP. I can browse to directories on the web server via windows file sharing, but browsing to web pages on that machine sometimes fails entirely or is super slow. If I check the browsing from an outside connection the server is delivering pages very fast. If I tracert a domain which is on that server it takes a single hop directly to the server (which would make you think it would serve up the pages extremely fast). No idea what is going on.

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