Port 32400: Plex Media Server
Port 32400 is the Plex Media Server port, used to stream your media library.
What runs on port 32400
Plex Media Server listens on TCP 32400 for its web app and for players on TVs, phones and consoles. Plex's Remote Access feature asks for 32400 to be reachable from the internet, through UPnP or a manual port forward, so you can stream away from home. Without it, Plex falls back to a slower relay.
On a home network
Any computer, NAS or Nvidia Shield running Plex Media Server listens on 32400. Seeing it on your NAS is normal.
If port 32400 is reachable from the internet
Exposing 32400 is what Plex Remote Access is designed for and is widely done, but it puts the server's software directly on the internet. In the 2022 LastPass breach, attackers got in through a DevOps engineer's home computer running an old, unpatched version of Plex. If you use remote access, keep Plex updated and the machine it runs on free of sensitive data.
How to check whether it is open on your network
In Plex, Settings, Remote Access shows whether it is reachable from outside and on which port. Your router's UPnP table shows whether Plex opened the port itself.
To find out whether port 32400 is open on something in your home, and whether the internet can reach it, the app scans your Wi-Fi from your phone and checks your public address from the outside. It says what it checked and what it could not. Get RECON for iPhone — one-time purchase, no account, nothing leaves the device.