2023-11-29, 05:48 PM
I think I figured this out! I have come to realize that around the same time that this problem started happening, my PiHole ad-blocking DNS server had started blocking cdn.jsdelivr.net due to an auto-updating blocklist (https://github.com/StevenBlack/hosts/issues/2515).
I had been using some URLs from that CDN to pull in some CSS from Ultrachromic (https://github.com/CTalvio/Ultrachromic) and these requests would have failed, but been undetectable in my server logs. Once I figured this out and added that domain to my whitelist (the domain has since been added back, but my blocklists hadn't been updated after that), things started working again. I guess web browsers will just silently fail and not apply the CSS if they can't reach those URLs, but the Jellyfin Android Client (and maybe the Android TV client?) will fail and appear to hang on the splash screen (Android TV) or kick you back to the server selection screen (Android) if those CSS URLs cannot be reached.
TL/DR: It really was due to a totally external factor and nothing to do with Jellyfin, although there may be a small bug in the Android client regarding the attempt to load custom CSS URLs that cannot be reached.
I had been using some URLs from that CDN to pull in some CSS from Ultrachromic (https://github.com/CTalvio/Ultrachromic) and these requests would have failed, but been undetectable in my server logs. Once I figured this out and added that domain to my whitelist (the domain has since been added back, but my blocklists hadn't been updated after that), things started working again. I guess web browsers will just silently fail and not apply the CSS if they can't reach those URLs, but the Jellyfin Android Client (and maybe the Android TV client?) will fail and appear to hang on the splash screen (Android TV) or kick you back to the server selection screen (Android) if those CSS URLs cannot be reached.
TL/DR: It really was due to a totally external factor and nothing to do with Jellyfin, although there may be a small bug in the Android client regarding the attempt to load custom CSS URLs that cannot be reached.