Hi Majestic_Cloud,
Thank you for using the Support Forum. Please make sure you have enabled the optional feature of the duplex unit in the driver. If the instructions do not help please consider contacting your support centre for further assistance.
System is Ubuntu Mate 16.10
connecting by USB cable
I installed using the PPD file from the .rpm driver download
The duplexer installed in front as instructed. Printer options set to "Flip Long Edge"
The trouble: Every 2 sided print comes out as 1 sided.
New printer, bought in January without warranty.