- Make sure that both your Plex server machine and the machine where the Plex web app is open have correct date and time set.
- disable any 3rd-party web browser add-ins temporarily and compare the behaviour
- investigate if your router is applying “DNS rebinding protection” and insert an exception from this protection for the domain name
plex.direct(if possible)
(background information: https://support.plex.tv/articles/206225077-how-to-use-secure-server-connections/ ) - verify that your local network is indeed using an IP address range that is reserved for “private” use Private network - Wikipedia
- perform Method 2.2 from this post: You need to reclaim your server, but don't dare to touch the Windows Registry
