I had to reset my Apple TV 4K and since then i cannot had Plex Server to Infuse. Indeed, although Plex Server is running from my Synology NAS, after validating the security code, i have the following error message : “An error has occurred”.
Manually update to the latest version of Plex media server (download the file from Plex and perform a manual install on your NAS). I ran into Plex issues on my Synology and this fixed the problem for me.