I just built a new Windows 2012 R2 server on an older Dell PowerEdge 1900. The server built very easily and the server is running very well. It is a pretty clean install, with nothing major installed other than AD and IIS. After it was built I installed a third party proxy server (safesquid). After it was configured everything seemed to be working well until suddenly no one could access the internet. I disabled the proxy on my workstation and I was able to access the internet. So I called Safesquid and after some troubleshooting, we found that it was the server. If I disabled the proxy the server could not access the internet. Since the server could not access the net, when the proxy was running, neither could the workstations.
So I reboot the server, and then everything was find again. A day later, same problem. I tried to reset winsock, but that just asked for a reboot which I know would solve the problem. I have rebooted the server three times in the past three days and each time it solves the problem. When the server looses the internet connectivity, it still has local network connectivity. I can access files from the server and from the server I can access my workstation. I checked DNS, and it is set up correctly.
Does anyone have any thought about how to troubleshoot this?