Guide: Plex setup

first of all, you must examine which internal ip address you are running with plex on the Nas server..
I use portainer, so it makes it easier for me to operate around the system and read the log and console

image below

I have found this internal ip which is under qbittorrent -> 172.17.0.2 the reason is that I have set my plex to run under qbittorrent's network with vpn. so that's why plex doesn't have its own ip

Plex: entry your localhost:ip address -> jump to settings -> network.
There are some settings you need to make sure are set correctly.
secure connections: Preferred.
Preferred network interface: Any.
LAN Networks: None.

Which next jumps to Remote Access
There you will find your IP address and how it registers in the local network and outside the network.

Private: Your internal ip 
Public:  Your hostname ip like 192.168.x.x
If you use VPN, then it would show different ip address

image below. - this image is set up with vpn address (Spoiler)

This is how my Plex setup looks on Homarr

Internal address: http://172.17.0.2:32400
External address: http://192.168.50.140:32400

Network: add "401" statucode

External address can be used different ip address.
This means that the internal address gets homarr access to the plex container. and external means that it forwards you to the other ip for access to the plex website.