How do I fix this? I hav e 25tb olf media on the NAS so I naturally assumed the Plex Server should be within this NAS also? Do I simply load the Plex Server onto my PC and then direct it to the media on the NAS as a work around?
You have a semi-old NAS that went QNAP OS EOL in 12/2017 and are stuck on QTS 4.2.x (32-bit) software. Plex no longer supports that as of Plex Server v1.15.x (64-bit only) due to Qnap’s lack of updates to core libraries/etc.
Your BEST option is place your Plex Media Server on another device (Intel PC/NUC, ShieldTV, etc.) and pull your media files from your QNAP via a 1GbE hardwired ethernet connection.
That way you leverage what your NAS is going to do best (serve/store media) and have Plex running on a more current HW platform that will be able to leverage all the current and future Plex Server SW enhancements.