[DiapDealer]

The port forwarding needs to be forwarding port 8080 (I believe) to your internal calibre machine's IP. That's if you're connectng to calibre's built-in server. If you're trying to connect to calibre's wireless device service (like with the calibre companion app) then that's a different port.

Another process needs to occassionally test and update your No-IP hostname address (unless you have a static IP that never changes).

The No-IP hostname might not work from behind your own router. The public IP could be sending traffic through your router instead of directly to your local machine.

Try accessing it from outside your own network to determine for sure if it's "working," or not. If it is, then you may need to add your local calibre machine's IP to the hosts file of the machines that need to access it from your own network.