congratulations!! greetings from shitjustworks

maybe you issued one certificate with multiple domains, mixing internet facing ones with purely internal. It is very easy to discover hidden subdomains inspecting the certificate you get from a public service

its not a special setup. you can log in to jellyfin using a web browser in your laptop and connect the hdmi to the tv. then this device appears in the cast menu, so you can choose movies or shows in your phone (jellyfin app) and cast them to the laptop