This is the email from HP Support received 02 June 2014:
"This is regarding the HP LaserJet Pro 500 color MFP M570dw Printer. For reference, your Case ID is 4646865779.
I would like to share the below information as you wanted to get with details instructions through e-mail on how to run the software.
Please open the ftp link: ftp://pri_111:rs!TT6dn@ftp.usa.hp.com
Download the file name “M570_fax_fix.zip”
Before you run the file, please read the below instructions carefully.
As the printer is currently connected to the computer using USB cable whereas you want to connect using Network cable, first please uninstall the full software of the printer from the same computer
Now, connect the printer over the network and make sure you have the correct IP address of the printer.
Make sure you are able to ping the same IP from your computer. Please install the full software of the printer using the IP address.
Once the full software is successfully installed and you are able to print from the same computer, please run the downloaded file by following the below instructions:
Unzip the file ““M570_fax_fix.zip”
In the folder, please right click on the “setup.exe”> select “Run as administrator”.
File will execute automatically.
Once you are done, try sending fax from the computer and check for the issue."
I HAVE NOT TRIED IT YET!