Connect to Plex through a PPTP connection from outside my home network

Hello guys,
I really need your help for short I want to conenct to my Plex Media Server from outside my Home Network. Normally this shouldn’t be a problem I also can connect to my Nextcloud from outside the Network but Plex is different.

More information about my network:

  1. I need to connect via PPTP to an VPN (in my router) to get access to my internet.
  2. I opened up Port 32400 internal and external.
  3. My nextcloud and the plex media server use the same device and have the same IP adress
  4. I use a DynDNS to connect to this device

When I enable the remote access to my server in the settings the text changes to green and says for about 5-10 seconds everything is fine you can reach your server from outside and after this few seconds the text went red and says “your server is not available outside your network.” I tried to use UPnP which also does not work.

What I really don’t understand is the fact that I can communicate with my Nextcloud from everywhere on Port 80 and 443 but not with the Plex server on port 32400. Did anybody has a clue what I can try next or maybe even a solution?

Btw. I use a NextcloudPI 1.18 Image on a ROCK64.
Server Version#: 1.17.0.1841
Player Version#: 4.8.3

I fixed it. I spoke to a network administrator and he told me that we have a very restrictive firewall and only a few specific ports for special uses open so I use one of these ports now and can connect from outside.