Don’t use jellyfin.server.local
.local is reserved for mdns, which doesn’t support more than one dot. (Though it may still sometimes work).
In any case, to make that work you need either a DNS server on your network or something like duckdns (which supports wildcard entries).
I feel like I’ve had the opposite experience in the gui (maybe a KDE issue?) closing gui windows frequently lock up, and I find I frequently have to drop to the command line in order to properly kill some programs