My Synology NAS would not successfully start Plex Media Server at bootup. I had to go into Package Center after each boot and run it manually.
I reached out to the Plex forums and didn’t get much help. I did eventaully find a fix.
I assumed that the script was failing on boot as it was waiting for some not-yet-ready resource, and would only run after the whatever-resource was ready. It just needed more time to be ready.
copy the “/var/packages/Plex Media Server/scripts/start-stop-status” file somewhere else on your NAS where you can edit it, and make the following edit:
...
start_plex ()
{
+ sleep 7
PLEX_PATH=$(/usr/syno/sbin/synoshare --get Plex | grep Path | awk -F[ '{print $2}' | awk -F] '{print $1}')
...
Save the file, and then copy it back to it’s original location. Reboot.
Plex Media Server should now run on boot successfully.