OH MY GOD
Edit, to add:
Once I figured out what my modem thought my router’s address even was that worked immediately. Jellyfin is still giving me one minor headache after another but it is working, and these are all issues I can solve.
Now I have the unenviable task of resuming work on ripping literally hundreds of DVDs.
It does have a secure password. The only reason I have that router is I didn’t trust the modem CTL gave me to secure my computer.