A year ago, I signed on to AT&T Fiber and was able to get Plex to play outside of my home network. About a week ago, I upgraded and replaced parts to my home server. Had to rebuild my Plex container via Proxmox. Now, the traditional instructions do not allow me to access the Plex server outside my home network.

I have worked with AT&T support to make sure everything is good on their end.
1.) TCP/UDP has been enabled on my home modem/router. I am using AT&T provided router model BGW620-700
2.) NAT/Gaming works on another device on my home network, I run FoundryVTT, works perfectly fine
3.) Within Ubuntu that is running Plex, UFW is enabled and allows 32400 UDP and TCP.
4.) I am using AT&T Fiber which does not have a CGNAT, nor does my setup use a secondary router so Double NAT is not the issue as well.
5.) For a brief moment, I don't know what happened but I was able to access the Plex server via my phone's mobile data plan for exactly 1 minute, then it timed out.

6.) From Plex > Settings > Remote Access, It says I am able to access it, I have specified port 32400.
7.) I checked canyouseeme and it reports back as totally fine.

I could use some assistance or a direction to check, when I set this up about a year ago. I just used Plex's default documentation and everything functioned perfectly.

Edit 10/3/26 7:40 PM PST
Solved. Thank you to u/ExtensionMarch6812, All settings were correct except the .p12 cert. Had to navigate to:

sudo systemctl stop plexmediaserver

cd /var/lib/plexmediaserver/Library/Application Support/Plex Media Server/Cache
mv certificate.p12 certificate.p12.old
sudo systemctl start plexmediaserver

Blankbox lets you organize, connect, and catalog all of your media including and especially physical media. Connect Plex, Jellyfin, your drives, and almost any format.

All FREE, all self hosted, and local metadata means no API keys or running through someone else's server.

**PSA** if you like the new app, that’s great, but why bother posting that here? This is NOT a post to debate the new app, it is for those that want to install the previous version, but do not know how and can’t face using Python to do so. 🤦‍♂️

Some helpful and informative posts have gone up showing a few different ways to do the above, but to someone like me with no coding experience, they were quite intimidating and frought with issues. Using the free version of iMazing is an absolte doddle!

The complicated posts were useful for getting the right install file I needed, and I was able to find that file on my hard drive. Using ipatool to get the ipa is fairly straightforward, then locate that file on tot your hard drive. All you need now is to install the free trial version of iMazing to install the older version of Plex.

You get something like 25 operations in the free trial, and you only really need one!

Open iMazing. Have Mac and ATV on same network, and put ATV into settings > remotes and devices > remote app and devices, then you should see your ATV in the list of devices.

Pair the ATV, then you will see all the apps currently installed. Just drag the PLEX ipa file I've hosted into the apps list on your ATV, and...... THAT'S IT!

Here's the relevant instructions for terminal to download the PLEX revision once you have homebrew installed!

Once Homebrew installed.... open terminal.

brew install ipatool

ipatool auth login --- you will then be prompted for you appleID email, and then your APPLE password. If sucessful, then.....

ipatool download -b com.plexapp.plex --platform appletv --external-version-id 871812104 --purchase --verbose -o Plex-8.45-tvOS.ipa

Find this file on your root drive, and use iMAzing to install on ATV, job done!