Hi 1yen.
Thank you for using the Community Forum.
If your device is displaying the message 'Duplex Jam 1 Open/Close Door Message: Paper Jam in the Duplex Area' please check this solution 1: Clear the Paper Jam from the Duplex Unit Area. It contains several steps and images displaying how to clear the paper jam. Check to make sure there aren't any slivers of paper from a previous jam that have not been removed correctly. This could also be causing the issue.
The product knowledge base has a few other steps to check out.
- Make sure the paper is within specifications
- Make sure the paper tray is loaded correctly
- Power the Machine Off, Wait 20 Seconds, Then Power On
I hope these help resolve your issue. If not, please consider contacting support through this link: Fast Track to the Expert