We have three of these printers. Two are functioning normally. One started printing very, very slowly (the page advances out of the printer at less than half the rate of the other printers. It also quit duplexing. After restarting, reinstalling firmware and removing and reinstalling the print drivers on Windows 7 pro (but it does the same thing from MacOS 11.6), it printed normally, for about 30 minutes. Then this morning it is back to the slow printing and refusing to duplex. We repeated everything we did yesterday but today it did not fix the slowness or duplex failure.