I recently purchased a used EcoPro EP C170N printer. When I got it home it seemed to be working fine. By working fine it printed very nicely and I could hang it on my network and communicate with it for printing with no issues. It has a wired network interface, not a wireless one. The only issue I had with this printer was that it did not have a duplexer. I went online and on eBay I found a new duplexer at a very reasonable price, purchased it and got it in. In the meantime I had taken the printer offline (unplugged it from the network and power) while I waited for the duplex unit to be delivered. Once I got the duplex unit I installed it per the directions (pretty simple you just set the printer on it and away you go). I tested it by setting the options on the front panel to tell it to duplex all the time and printing some multi page status pages and it worked just fine. I did not alter any other settings. I then connected it back to my home network and it would not communicate via the network. At first on the front panel it said NET LT PLAIN and after a few minutes the display changed to --- LT PLAIN. I tried multiple times to review and even change the network settings through the front panel and had the same end result no matter what I did. I then unplugged it from the network and connected to it via USB and was able to communicate and print just fine that way. I even went as far as to remove the duplex unit and tried plugging it back into the network and still no luck. As a last resort I slipped the network board out of it and tried reseating it thinking maybe i had a bad connection. At this point I'm at a loss. Does anyone have any suggestions that might help me get this thing working again? If not the only other thing I can think of is to get a USB print server and hang it on the network that way. I've even looked for a way to do a factory reset through the front panel and have had no luck there. Any ideas, any help would be greatly appreciated.