NAT Loopback only effecting one device

I recently got a new modem/router (Technicolor C2100T) and I have a server (Ubuntu 16.04) with everything properly configured. With my old modem/router I was able to access the server from the public IP. With the new one I can't, but only on one computer (Windows 10). I could use the same computer and access it before. I didn't change any settings in the computer since installing the new router.