Hello,
Please try the below listed steps..
1>While the printer is ON, unplug the power cord from back of the printer and then Computer.
2>Power off the Wireless Router.
3>Wait for 60 seconds.
4>Now plug in the power cord to printer only.
5>Check for the error. if error shows up go to Step# 8
6>Now Power on the Wireless router.
7>Check for the error. If error shows up, then contact your ISP and check for firmware update, set the channel to 11.
8>If issue still shows up, then contact HP for further Assistance ( it could be a printer hardware issue ). If you are in USA, call 1-800-474-6836