I suspect you’ll need to add the
192-168-78-58.11565f46484d47ab9925586c8e7b7843.plex.direct
to your hosts file on the platform you’re running OH on and point it to your actual Plex server.
e.g.
192.168.78.58 192-168-78-58.11565f46484d47ab9925586c8e7b7843.plex.direct