Diagnostics (repeating several things said above):
- Can you ping your server from the public network? If not then something is blocking packets.
- What does a traceroute of the public address from the public network give you? It should go all the way to the calibre server. If it does not then you will have a clue where the traffic is being stopped.
- Is the firewall on the calibre server set up to accept packets from the router?
- Is the firewall on your router set up to allow packet forwarding? Many refer to this as "setting up a DMZ".
- Are you really testing from outside the local network, for example from the cellular network? Lots of routers will not forward packets from the private network back to the private network.