First of all, why would PMS ask me to log in to Plex_tv when started from localhost (making an actual redirect to app.plex.tv/auth URL), how would that work if i don’t have any internet connectivity on the subnet PMS is located on, and how do i work around this “feature”? I added my subnet modifier to “no-auth” section, but to no avail. Is having a Plex_tv account mandatory in order to use PMS on local network?
Secondly, why would i enter some four-letter code somewhere on the internet in order to connect my local TV to my local instance of PMS? Again, how would that work with no internet connectivity? How do i pair my Plex TV app with a local PMS?
Yes, usually you can survive temporary disconnects without much trouble (unless you need to authenticate against your plex account - which of course is impossible without connection)
Probably not. At least not authenticated with several different users.
But Plex needs internet not only for user authentication but also for
downloading codecs on demand
looking up and downloading metadata for movies, tv shows and music
access to online-based media
so running it totally without connectivity is not possible (or at least impedes regular operation of Plex in a way that you’ll don’t want to suffer it.)