Custom server access URLs do nothing

I am behind VPN and Double NAT , I have correctly forwarded the ports. I know remote access should work fine using my Dynamic DNS Domain name and port.

On the plex remote access page it keeps detecting my VPN IP instead of my public IP, Can we just have a box were we could just put in an IP address for remote access. I also tried using custom access URL , still no remote access , All I am able to do is get a an Indirect and unsecure connection to server.

How can a application meant to be run as a server not have advance options to configure network parameters.

I ran a trace route within firefox , It did seem to show my custom access URL. Thanks for the help.