HTTP 500 (No authority could be contacted for authentication.) in SharePoint

I was getting an HTTP error 500 after restoring my SharePoint development server in a different network (at home). The thing was a bit curious because I could see the SharePoint site from the virtual server, but not from my physical server and yes, I checked the IPs and they were OK. The first thing I did was to configure the IE9 to show me the HTTP errors the way I like them, the “unfriendly” way.

To do so I went to Tools –> Internet Options –> Advanced, and there in the tree below Browsing I unchecked the “Show friendly HTTP error messages”.

After that I could see that the problem I was having when connecting from outside was “No authority could be contacted for authentication.” Here I saw that the easiest way to fix the problem was to remove the server from the domain and then add it again.

And it worked... Finally…