I think you’re on the right track, re-claiming. Why it didn’t work? Well, there are a number of variables. So let’s just try to get you back up rather than putz around.
Step 0: Power cycle every piece of hardware in your network and your Linux box.
In another topic I explained for Mac how to Reclaim from the command line and you could follow steps (1) (5) & (6) in the tunnel, then grab 
cuz that’s gonna work.
I suggest that you clear your history, cookies and cache, then restart the browser. That way you’ll get a nice Plex Sign-in when you use Plex | Claim.
