HI!
Are you using the FreePBX firewall?
Maybe it is blocking that port…
I don’t personally use the FreePBX firewall but if I did I would make sure that traffic to that port is allowed…
When I saw your post I wondered why you would want to do that though…
Is it because you want to access many servers behind the same IP or because you want to have your PBX web interface listen to the Internet and instead of allowing access by IP you make it listen on a weird port?
Good luck and have a nice day!
Nick