Plex used to work just fine, but now when I start it up on my Syno NAS and go to [http://192.168.0.101:32400/web all my content is gone and when I click on the “Add your media to Plex” I get to a splash page with a big button that says “Get Plex Media Server”
When you try to open the server, are you using http://ip.addr.of.syno:32400/web ?
I suspect you are.
If you’re already signed into your Plex account, SIGN OUT
Now repeat.
If that fails, I will ask the next question: Are you and the Syno on the same RFC-1918 compliant network (192.168.x.x, 10.x.x.x, or 172.16.x.x-172.31.x.x) ?