Scan to Network Folder Error: "The network folder path specified does not exist."

[SM_123]

PRODUCT:  HP LaserJet 500 color MFP M575

NETWORK: Two 64-bit Windows 10 PCs, (PC Alpha and PC Beta) and the M575 all connected via their own Ethernet cable to the same router. 

HP FIRMWARE: the latest available (December 2019).

Printing works fine and the M575's settings are accessible via web browser interface from both PCs. 

THE PROBLEM: The M575 has been configured for years to scan to a shared network folder on PC Alpha. This has worked fine for years until today.  When we try to scan we get an error message, "The network folder path specified does not exist." Attempting to verify the path from within the Quick Sets Setup, produces the same error.

We have disabled antivirus and firewall on PC Alpha.  Accessing the M575  via the browser, we go into Quick Sets Setup > Edit Network Folder Path, and verify the UNC Folder Path is looks correct.  To confirm this, we click Update Preview and copy the Folder Path Preview and paste it into Windows Explorer on PC Beta and the target folder opens immediately, which confirms that the path is correct and the folder is shared.

The last time we are sure it was working fine was two weeks ago.

What else can we try?

[SM_123 · Accepted solution]

FIXED IT!

SOLUTION: 

Quick Sets Setup:  Edit Network Folder Path : Save to a standard shared network folder :

Remove "WORKGROUP" from the Windows Domain field

[PB90]

No Change.

Error still persist.

I Have Remove the WORKGROUP.

The Panel shows a long time Check Access, then the same Message Appears.

Same Error Message wenn I will sent to FTP.

Newest Firmware is installed, reset to Factory settings also.