You seem to be addressing two issues.
1. Issues with your remote access setup
Did you already have a look at the related troubleshooting support article?
https://support.plex.tv/articles/200931138-troubleshooting-remote-access/
There’s also a guide with some more details on how to troubleshoot remote access issues. If you cannot get it working, the outcome of the individual checks should provide additional pointers for others who can help here.
2. Listing of a show in Plex’ Discover pages
Discover isn’t giving you access to any media – it’ll only show you where a show is currently available (first checking the services you’ve set in your preferences; with an option to check out any other services in your region). For me the show is listed as available to purchase on Apple TV / Amazon / Microsoft or to stream with a Netflix subscription). From what region are you trying to stream the show?
