Could you set the IP address directly on the client? Instead of assigning a static IP on the router. If you can't set a static IP on the router, I wouldn't be surprised if it wasn't handling local DNS properly.
Jellyfin 10.10.7 (Docker)
Ubuntu 24.04.2 LTS w/HWE
Intel i3 12100
Intel Arc A380
OS drive - SK Hynix P41 1TB
Storage
4x WD Red Pro 6TB CMR in RAIDZ1