For the caddyfile, can you try using the LAN IP of the host instead of "jellyfin"? If you removed the port publishing you'd use the container's bridge IP instead.
Jellyfin 10.10.6 (Docker)
Ubuntu 24.04 LTS
Intel i3 12100
Intel Arc A380
OS drive - SK Hynix P41 1TB
Storage
3x WD Red Pro 6TB CMR in RAIDZ1 (JF Library)