Linux-hosted Plex server sporadically losing Remote Access

Plex Media Server Remote Access
1

Server Version#: 1.43.4.10903
Player Version#: N/A (Applies to Sonos, Web)

I am hosting my own Plex server on a Fedora 44 server. It works flawlessly on my LAN. Wanting to play music through my Sonos system, I have authenticated the Sonos system to Plex.

Data points:

  • My ISP is Google Fiber.
  • I have an Unifi UDM SE gateway/router.
  • I portforward tcp/32400 from my WAN interface to the IP of my Plex server.
  • My Plex server has a static IP on the LAN.
  • I have a dynamic DNS entry set for the hostname of my Plex instance. It resolves correctly on 8.8.8.8 (for instance).
  • I am using the default Plex SSL certs.
  • I am not using IPv6 for Client Network.
  • I “Require” secure connection, and require Strict TLS config.
  • I am not publishing a custom server access URL.
  • I am using the Relay option.
  • I manually set the public port to 32400.

The “Remote Access” entry will show “Not available outside your network”. The section immediately below shows a green arrow from <public IP>:32400 to <private IP>:32400, but a red X from “Internet” to <public IP>:32400.

If I click “Retry”, “Remote Access” switches to “Fully accessible outside your network”, and “Internet” shows a green arrow to <public IP>:32400. Sonos starts playing.

Navigating away from the “Remote Access” menu and then back, the status is now “Not available outside your network”, but the Sonos keeps playing, until it stops (runs out of buffer??) and then is unable to reconnect.

I feel like I’m missing something very basic, but I cannot for the life of me figure out what it is. Anybody immediately see any dumb I’ve committed?

Thank you!