HP MFP M277dw prints from Macbook but-- suddenly-- not from iMac

[MonmouthNJ]

HP MFP M277dw has for years printed wirelessly from network-- still does for MacBook Big Sur 11.6 . . . but not (starting yesterday) from iMac with BigSur 11.6.   

I printed  Wireless Network Test Report from printer and everything is "Pass" with signal strength "Very Good" and the right network name.  There is a "Troubleshooting" note about "More than one wireless/router that matches your wireless network's name." I don't really understand that . . . but for years there has been no problem, and I did not change anything. (Though I did restart the iMac.)

[GOLD_MASTER]

Hello @MonmouthNJ .
Waiting for some other comment from an expert or other user, what I can provide is a very basic help on the subject, but you can try to do the following:

Update the printer firmware:
https://ftp.hp.com/pub/softlib/software13/FW_CPE_Consumer/M277_K5/M277_MFP_Series_FW_Update-20201119...

Upgrade instructions:

Spoiler

Instructions for the HP LaserJet Pro MFP M277 M274 series Printer Series Flash Firmware Update using Mac OS operating systems: Flash Firmware Update Notes:

• The Firmware Update Utility can use either a Network or USB connection to the printer.
• When using a Network or USB connection, the HP MFP print driver software must be installed prior to using this utility.
• The HP MFP printer must be on and in a READY state as shown by the LCD display on the control panel and remain powered on during the entire firmware update process.
• Depending on the processor speed of your pc, the firmware update process may complete on the printer before the update status progress bar in the flash firmware update utility on the pc screen completes, this is normal.
• Once the update process has started, do not use your pc for any other activity until the process is complete.
• Inform others connected to the product, both network and USB, to refrain from using the printer during the update period.
• Do not power cycle the product or the pc until the firmware update process is complete.

Process:

• 1.Download the flash firmware updater file from HP.com to the pc desktop.
• 2.Turn the printer off and then back on to clear main printer memory.
• 3.Double click on the flash firmware update utility file. An HP firmware update window will open.
• 4.Select the appropriate MFP in the dialog window. If you assigned a different name to the HP MFP, choose the name that represents the correct printer.
• 5.Click on Send Firmware when ready to proceed.
• 6.The progress bar will begin to move to the right indicating information being transferred.
• 7.DO NOT power cycle the product or the pc during this process or the product may become unstable and or unusable without further attention from HP. The flash firmware update can take up to 5 minutes to complete. Please be patient.
• 8.During the product flash firmware update, the display on the product control panel will display Erasing - Programming - Complete - Hewlett-Packard - Ready - Initializing - Ready. Once the download is finished the printer will be in the Ready state.
• 9.At the conclusion of the firmware update, the dialog window will show a smiley face. Click on exit.
• 10.The flash firmware update process is complete.

If it is desired to verify the update, use the control panel reports menu under setup, to print a configuration report. The configuration report will show the current firmware revision in the Product information block.

• Mac: Use Diagnose & Fix through HP Smart. Learn more here

1. Run HPPSdr.exe from the download location on your computer.
2. Once HP Print and Scan Doctor is open, click Start, and then choose your printer.
   • If your printer is not listed, turn it on and click Retry.
   • If there is a connection problem, follow the instructions in the tool.
3. If a screen displays prompting to turn on printer updates, click Yes and continue.
4. If a screen displays prompting to make your printer the default printer, click Yes and continue.

[MonmouthNJ · Accepted solution]

Thank you, Gold-Master.

The firmware/software was up to date, and the iMac (my OS is 11.60) using Scan Doctor could nor detect the printer . . . it was offline!

The problem has been solved-- I think maybe by simply turning the printer off then on several times. Or maybe by raising my home network to the top of the network list, where it had drifted down below many hotels, airports, etc.

I appreciate your help. (Though I think you may have been assuming I was on a Windows machine.)