Move Metadata to an External SSD

[Wellington_Boy]

I have an 608T Asustor NAS, with all drive bays full. Which I mainly use to run Plex for my household.

It plays everything just fine, with all my clients wired and capable of direct playing without transcoding. However, as the collection has grown the interface has become as slow as molasses. Using the Android app to initiate streaming is taking longer and longer to load the metadata. Often the orange spinning circle just times out.

I have an external 500GB USB SSD that I can connect to the NAS, and the NAS sees it just fine. I want to use this to the Plex metadata (currently on /Volume1/Plex/Library), to make the system more responsive. I can copy the metadata to the SSD. However, I can't seem to make Plex to then use the new location for its metadata. The setting to relocate metadata in Settings > General > Advanced for the Windows version of Plex doesn't seem to exist in the Asustor version, and there seems to be no setting to do this.

I'm not an IT professional. So for the more technically literate Plex users here: Is moving Plex metadata on an Asustor NAS to an externally connected USB SSD NAS possible, and if so how would I do it?

Any help greatly appreciated