Why can't I connect to minecraft server?

My fiance has had a minecraft server for several weeks now and I have always connected to it without any issue. Today, I went to access it and it tells me "can't connect to server". I have tried to access it from a different computer, uninstalling and reinstalling the minecraft.exe, and tried re-adding the server. Nothing has worked. If you log onto the computer that the server is on, you can access it. You just can't from any other computer. Any Ideas?

Added (1). Nope, the Ip is still the same. We even dropped the firewall and that didn't help.

Did his IP address change?