Plex app works on phone but not my browser?

[OttoKerner]

The “mobile” apps contain a workaround, but the affected apps do not.

Why can I access my server on some public networks, but not others?

Some ISPs provide rather weak DNS servers which don’t resolve the .direct top-level-domain (reliably). This is needed when the Plex server has set the ‘Secure Connections’ ‘required’ preference. In such a case, the TLS certificate is ‘pinned’ to only the exclusive subdomain for your server which is is on the *.plex.direct domain. If the router of the public WiFi cannot resolve this Domain name to a IP address, your plex client cannot talk to your server because it doesn’t know its IP address. …