Huh. I made a big comment reply to this and missed a crucial detail. Are you trying to just make it so that sitting in your own home, you can go to plex.mydomain.xyz instead of the IP?

What are you running plex on? Windows or Linux? On Linux, you can run this thing called Avahi. With it, you can set it up so that your computer starts advertising locally as whatever domain you specify. So I have server.local and newserver.local internally. I just go to server.local on my browser inside my home and it takes me to the landing page of the server where I’ve got Heimdall running, which has links to plex and a bunch of other internal services I’m running.

I don’t know what the equivalent is in Windows, but we can jigger something up. Let me know what OS you’re running on what boxes.