2 things to check:
- Locate the preferences.xml on your system. if the preference
disableRemoteSecurityis set to1, shut down PMS, then set this to0 - Make sure your server is signed in to plex.tv (take a look at Settings - Server - General) then go to Settings - Server - Network - ‘Show Advanced’. If the field ‘List of networks that are allowed without auth’ is empty, fill it with
127.0.0.1/255.255.255.255. Then click on Save Changes. To be sure, restart PMS.