There was a problem claiming this server on setup

[nibbles]

Paul that sounded like a long day, I’m sorry to hear that.
ChuckPA created a new utility for claiming:

Server credential reset utility for Linux-based platforms

Plex Media Server User Credential Reset Utility In light of the security event plaguing everyone, a ‘quick & dirty’ tool was crafted. It’s a little rough around the edges but gets the job done. It’s been evolving due to the need. This tool, Removes the existing Username, Mail, Token, and PlexHome preference values from an existing Preferences.xml file leaving the server now suitable for claiming. Reclaims the server via a user-entered “Plex Claim Token” (obtained by visiting https:/…

Take a few minutes to consider that thread.
The Synology FAQ is also great. Your videos and metadata should be okay.

Synology FAQ - Questions, Answers, and How-To's

Synology Frequently Asked Questions Table of Contents Intro: Posting in the Plex Synology Forum DSM 6 & 7 FAQ Some of these FAQ apply equally to DSM 7 and 6. Others do not. Please read carefully before proceeding. Getting access to the Logs Have I installed the latest version…? Which version do I need, Intel or ARM? 3a. Using Plex’s package signing public key - DSM 6 LAN addressing requirements - RFC1918 specification for local LAN? First run & Setup Recommended Media Organization and A…