HP 7520 WiFi scanning not working Mac OS High Sierra
If when installing an HP 7520 WiFi printer with HP Easy Start you get a warning that the scanner does not support “Bonjour” then you may end up with a working printer but no scanner!
In most cases this happens because you have a dual band router advertising 2.4GHz and 5GHz on the same SSIDs. In short the HP 7420 only works with the 2.4GHz network.
One solution is to disable the 5GHz network or rename it and only connect the Mac and printer to the 2.4GHz SSID network. This may have to be done manually, i.e. entering WiFi password from the printer front panel. Once connected (ping test with printer ip address) uninstall the HP printer software using HP Uninstaller and reinstall the printer using HP Easy Start. This time you should not get the warning message and have both printer and scanner working.