QNAP TS-253A PMS unable to find HDHomerun Quatro

This is so odd!

And gloves off :wink:

First, find your Plex Token, and take a note of that
Ref: Finding an authentication token / X-Plex-Token | Plex Support

Then make an SSH connection to your QNAP
Ref: Qnap faq.....read me first!

In the terminal window, type:
curl http://127.0.0.1:32400/media/grabbers/devices?X-Plex-Token=<INSERT_TOKEN_HERE>

Then show us the output, and when doing so, make sure to HIDE your token!!!

After that, also in the terminal, type:
curl http://192.168.1.99/discover.json

And show us the output from that as well