Plex not accessbile outside of network

Hi,

I have a Plex Server that has been working fine. However now I am unable to access the server outside of my network.

I have enabled DMZ on my router, to exclude routing issue. As you can see on the screenshot, if I connect to the server through Plex.tv it shows an indirect connection. If I open it through my external IP address, I can access the server directly. If I open it on an LG TV outside of my network it’s unable to connect.

I have tried the usual restart routine without any luck. Any troughs about what might be the issue?

Best Regards,
András

I managed to resolve the issue, by manually specifying the 32400 port. But someone please explain to me from a technical point of view, why does it work with a port forward, but not with a DMZ?