Unauthorized error when connecting to Jellyfin server on Apple TV (tvOS only)

[FabulousSoldier]

Moonfin version: 1.4.0
Platform: Apple TV 4K
tvOS version: 26.4
Jellyfin server version: 10.11.8

Description

Moonfin 1.4.0 on Apple TV 4K (tvOS 26.4) always returns "Unauthorized"
regardless of connection method. Other Jellyfin clients on the same
Apple TV work fine. Moonfin on iPhone (iOS) connects to the same server
without issues.

No device or access token appears in Jellyfin after a failed attempt,
suggesting the auth request either doesn't reach the server or fails
before a session is created.

Steps to Reproduce

1. Open Moonfin 1.4.0 on Apple TV 4K (tvOS 26.4)
2. Enter server — tested:
   • http://192.168.x.x:8096 (local IP, no SSL, no proxy)
   • https://jellyfin.example.com (HTTPS via NPM reverse proxy on VPS)
3. Enter username and password → "Unauthorized"
4. Quick Connect → also fails

What I've Tried

• Apple TV restart
• App delete + reinstall
• Local IP:port (HTTP, no proxy)
• External domain (HTTPS via NPM)
• "Hide from Login" disabled and enabled
• Quick Connect
• No token/device appears in Jellyfin dashboard after failed attempts

Working Clients (same server, same Apple TV)

• Swiftfin on Apple TV 4K (tvOS 26.4) ✅
• Moonfin on iPhone (iOS) ✅

Suspected Cause

Possible compatibility issue with tvOS 26 networking or authentication
APIs. Since no session/token appears server-side after the failed
attempt, the issue likely originates in the tvOS client's auth request
(e.g. missing DeviceId or App header field).