it couldn’t find any servers locally on my network, so I had to use my IP address. So when (not if) that IP changes I’ll have to troubleshoot.
One workaround that I can think of is to use ip reservation to give your devices the same ip address whenever they connect. You might find that setting under DHCP on your router. Or just use a static ip on the server.
I might be asking a dumb question here, this is the right community for that after all. But have you asked your cousin what might be wrong?