Can't connect my wireless HP m28 printer. keep getting error message

[Rongo2]

cant connect all of a sudden. worked fine up until yesterday. 

[Nal_NR]

Hi @Rongo2 , 

Welcome to the HP Support Community.

I understand that you are facing connectivity issues. I’d like to help!

To provide you with an accurate solution, I'll need a few more details:

Make sure, your printer and your device are on the same network as 2.4GHZ only.

Meanwhile, perform the steps below.

Use the Cancel and Wireless buttons to restore Wi-Fi setup mode.

1. Press the Cancel button 

    to ready the printer.

2. Press and hold the Wireless button 

    until the Attention light blinks.

   NOTE: 

   Your control panel might look different than the following example, but the steps are the same.

   1. Wait 60 seconds until the Wireless light blinks blue.

   2. Within two hours, return to the app or software to find and add your printer and complete the setup.

      You may also refer to this document for further assistance. 

      Update Firmware: Click here

      Hope this helps! Keep me posted for further assistance.
      Please click “Accepted Solution” if you feel my post solved your issue, it will help others find the solution. Click the “Kudos/Thumbs Up" on the bottom right to say “Thanks” for helping!

Is it a private (Home network) or a public Wi-Fi connection? Wi-Fi direct? Or Hotspot?
What device are you using the printer with a Windows computer, Mac, Android, or iPhone?