HERE IS THE SOLUTION: If you've recently switched from 2.4GHz to 5GHz wifi - this is the problem! Brother printers cannot connect to 5GHz wifi, but if you ask your internet provider, they can split the combined network into two separate networks, a 2.4GHz one and a 5GHz one - then connect your printer to the 2.4GHz!! I spent far too long trying to figure this out, so I hope this saves someone the hassle.