Setup stops partway through
During setup the printer broadcasts its own temporary network and waits for your phone or computer to find it. It doesn't wait indefinitely, so stepping away partway through leaves you with a printer that has quietly dropped out, which looks like a failure but isn't. Start again and stay with it. One thing that trips people up here: your phone has to leave your home Wi-Fi and join the printer's temporary network for a moment, and some phones jump back automatically because the printer's network has no internet. If that keeps happening, turn mobile data off for the duration of setup.