Using a Fritzbox 7490 I couldn't detect a WiFi printer from my laptop.
Printer suggested checking the "privacy separator" setting.
Sure enough, by default, the Fritzbox does not allow WiFi devices to communicate with each other. This is good security practice, but until I can wire in my printer I need to disable. It's done like this:
Select "The active wireless devices below may communicate with each other", and press "Apply". Bingo, I can print again.
