Regarding remote access, the public port must be different for all three servers. The internal port is always 32400.
You will have three port forwarding statements, one for each Plex server, each with a different public port.
In Settings → Remote Access + Show Advanced, you must check the box for Manually specify public port, and enter the external port number for that server.
Example: Note the different external ports
| Server | Internal IP Address | Internal Port | External Port | Protocol |
|---|---|---|---|---|
| PMS1 | 192.168.1.10 | 32400 | 32400 | TCP |
| PMS2 | 192.168.1.20 | 32400 | 32500 | TCP |
| PMS3 | 192.168.1.30 | 32400 | 32600 | TCP |
For port forwarding with an AT&T BGW-320, see this post: Changed ISP - No Remote Access with AT&T BGW 320-500 - #3 by FordGuy61. Substitute your servers for the Western Digital NAS.
