I am having the issue described here: https://support.plex.tv/articles/204281528-why-am-i-locked-out-of-server-settings-and-how-do-i-get-in/
I followed along step by step for a Netgear ReadyNAS. This did not solve the issue. I also logged out and back in via Http://myNASip:32400 (I see other servers and Plex Cloud).
So now I have removed Plex and reinstalled, and still nothing. Also Now Preferences.xml seems empty.
How do I get my Plex Server back?
ReadyNAS 6.9.3
Plex 1.13.2.5102.XXX
Connecting Via external/internal IP or LocalHost Name.