You described a problem for the JBoss but really the problem is other I think,
If you use LAN and LOCAL IP, JBoss is binded to LOCAL IP and ports and it's needed to set of rooter (if you use rooter with real IP) exact forwarding for some local IP and port to real IP of router and free port.
If you use direct real IP it's possible your Internet provider to be configured for refusing of your chosen port and try with other.
If you have proxy the problem maybe is in his configuration...
Really there are a lot of possibilities...