The PlexMediaServer package is only officially available through Synology Package Center, their download server and Plex.tv/downloads. What is “Qunhi”? It does not sound official.
It sounds like you were previously using Plex on DSM 6.
When Synology designed DSM 7, they changed everything about how applications work.
While the detailed information is here:
I suggest you read it thoroughly so as to understand what was changed and why.
While it’s too late to save what you previously had, It is directly possible to upgrade Plex for DSM 6 → Plex for DSM 7.
In Summary:
- Shared Folder: Plex → PlexMediaServer
- User: Plex → System Internal User: PlexMediaServer
- Privileges: All DSM 6 privileges have been stripped. DSM 7 Plex has no ‘root’ or ‘admin’ privileges of any kind.
There now exists several How-To’s to use DSM 7 PlexMediaServer in order to help folks adapt to the changes Synology forced with DSM 7.
If you examine the FAQ, they have been updated to support DSM 7.
New FAQ info has been added for DSM 7-specific issues.
