I am running Windows 8.1 Enterprise fully patched and latest full solution downloaded from hp. I have a LaserJet Pro 400 MFP M475dn updated with the latest firmware. The printer is setup on a wired network. I can print and scan just fine. I can send and receive Fax from the console. When I attempt to print to fax or run the HP Send Fax utility I get a Fatal Error Unable to communicate with the device. If I connect a usb cable and configure the printer I can select to send a fax via usb and it works just fine. I have 2 laptops one with 8.1 Enterprise and the other with Pro, they both have the same problem.
I Have no problem with Windows 7 or 8 (64bits both) Any Ideas?