Hi - I'm happy to help with your Mac issue. Please remember to Accept when we are completely finished and you are satisfied with my answer.
You need to install the printer first by connecting directly to your USB port. The drivers will then be available when you unplug it, and reconnect back to the Airport. Delete the USB connection and add the Airport connection in the set-up printers config and you should be OK.
Thanks very much. It's working now.
Sorry, that I have to come back. The printer was working. As soon as I restarted, the printer was offline. I have than used HP setup again and now device has shown up. I clicked on no, device shown up and than L7780 showed up. I pressed continue and than the message did show up Error 30886