Plex won't recognize server on Qnap TS-251

Plex Media Server NAS & Devices
2

https://support.plex.tv/articles/200288666-opening-plex-web-app/
and of course the Qnap faq.....read me first!

If you’re still stuck, follow up with your network details and the computer you’re using to connect to the QNAP.