Mind sharing some more details?
e.g. in what situations is your Plex client crashing (during playback, while browsing your library… local streaming/remote streaming… new/old player… issues with specific files / file types…?)
I’m using the same model in my bedroom and so far had no issues with the Plex player (1st Gen iPad Air, iOS 12.4.5, Plex for iOS 7.2.1). Edit: I used to have some issues in the past in combination with visualizers – but those have been fixed months ago.
Watching a movie or tv show. Searching (occasionally). Doesn’t matter what movie or show. Gets worse the longer I go between restarts. Usually get first crash after an hour or so. Deteriorates so badly that I cannot start watching. Crashes as I open a show. Worse when I leave something part way through, then try to restart.
Today, I’ve restarted my iPad four times just to watch a 90 min movie.
It is getting worse. Used to be the odd crash, needed restart rarely. Now restarts several times a day.
Have you tried to wipe the Plex app from your iPad, reboot it and add it anew from the App Store?
As mentioned above… I’m running Plex on the very same setup without issues. So there seems to be something specific to your setup.
Is there anything specific to your setup that could interfere with the Plex app (not sure what to look for… could be a bad jailbreak, some „security apps“ that mess with the setup…)