To those still having connectivity issues where PMS reports “unavailable” to outside users after hours/days of starting up and running correctly - this is a possible fix that worked for me after months of agony. I had the same Plex user account password for all my devices for years, and this token refresh was the solution. Thanks to @sa2000 for working with me months ago to figure this out - as this is something I wouldn’t have tried otherwise:
Getting a New Token
In rare cases, you may find yourself wanting to invalidate an existing token so it no longer works and get a new one. This isn’t something most users will ever need to do.
The easiest way to do so is to go to your Plex account profile, choose to change your password, and check the Sign out connected devices when setting your new password option when entering the new password.
This will invalidate all of your tokens and, as the implies, sign all of your apps (and any Plex Media Servers) out of your account. When you then sign back in, you’ll re-authenticate and get a new token.