Excuse the basic questions but I’m not having much luck web searching for answers. I have the server running on my laptop which is also where the content itself if and I have an android phone with the mobile client installed via f-droid.
I can’t seem to cast to chromecast with Jellyfin from either the laptop itself, or the android client app. The client app lists streaming to chromecast specifically as one of it’s features in the description on f-droid.
Try connecting to jellyfin’s IP address instead of the hostname. Google forces the Chromecast to use their own DNS that doesn’t know how to find your jf instance. I saw that exact same behavior when I was connecting to jellyfin.domain, it works when I connect to 192.168… though.