not a plex user but someone buried the lede here... to me, this is the neon sign that screams GTFO:
we noticed that you've accessed libraries in the past
what business of yours is it to notice my private comings and goings?! what other actionable intel do y'all keep in your logs?! bye!
I ran something similar a while ago; it automated the steps you're describing so it downloaded every new video from the channels I'm subscribed to along with metadata. I gave that up as it's hella inefficient. what I have now is just a media sink by way of macast and I can send videos for playback to my media PC. so if you don't need those videos for archiving purposes, try it out.
don't go with server variants of the OS. they are intended for boxes that work without display and keyboard, which you have. instead, install any normal distro you're familiar with. it's infinitely easier to fix something with the full GUI at your disposal.
this is just your first install, you will iterate, and through that process you'll get better and leaner, in terms of underlying OS. think of it as training wheels on a bike, you'll pull them off eventually.
wired connection only, leave wireless turned off, and assign it a static IP address.
don't do containerS, do one container first. figure out where you're gonna store the compose files, where it will store data, how you will back that data up, etc. then add another. does it fit into your setup? do you need to modify something? rinse. repeat.
casaOS, aside from it's murky background (some chinese startup or sumsuch, forgot?) doesn't provide that path forward nor allows you to learn something, too much hand holding.
good luck.
firstly, tlp is a powerful tool, but you need to configure it before letting it loose, identifying components you don't need and can be powered down, figuring out power limits, etc. that's too much work for me. also, if you're on ppd, maybe try switching it with tuned and tuned-ppd, which are now default on Fedora.
can't help with your specific machine, here's what works for me. what I want is a powerful laptop that works as a workstation when on AC, sips power when mobile, and has no significant power drain when left in standby for days. so:
using Plasma, as it has (among many other benefits) different power settings for docked and on battery. so it has generous power settings on AC and then rather conservative ones on battery, and
implementing suspend-then-hibernate. the laptop sleeps normally when not used, but if not used in an hour or so, it suspends to disk and turns off all power - no more battery drain. on powering up, it resumes from disk back to how I left it - faster than cold boot!
this brings it super close to stuff I had back in the macOS days - a laptop that I can leave for days and when I pick it up heading out the door I know it has a charge.
tl;dr - attacker needs to be connected to your wifi to exploit it. wish they'd lead with that.