i have a phaser 7800 dn, driver is XeroxPrintDriver_3.123.0_1865, i'm working with on an iMac, os sierra 10.12.6 (16G1212). after 10-15 hrs the printer suddenly reboots (mechanician says, currency of office is ok), and then printer driver is searching for printer for 15 mins, see screenshot. timeout repeating for every print job. next morning the problem is solved, after 10-12 hrs this happens again. configuration print is no problem.