Stop jellyfin, try renaming /etc/jellyfin/system.xml and network.xml (add .orig to the name or something), start jellyfin. It will regenerate those files with defaults.
Jellyfin 10.10.3 (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)