Seems to be the former from what I can tell. Unsure about the latter. My phone was yelling a generic "Saved / won't connect with current security settings", and wouldn't connect when I tried to turn off mobile data and force it to connect. After trying to force it enough, it prompted me for a password, and nothing changed when I re-entered the password.

I checked the NBN modem and it had solid green lights for up/downstream, power, and internet, so I'm guessing it's a router problem. LAN still isn't working, with any device, although the wifi is now fixed after a reboot 🤷‍♂️