The printer's address keeps moving
Print the network status sheet from the printer's own menu, under network settings. It tells you which network the printer joined and what IP address it's holding, and two minutes there beats an hour of guessing. If the network name matches your computer's, the address is the problem: your router hands out a new one after a power cut and the computer keeps posting jobs to the old one. Log into the router, find the printer in the connected devices list, and reserve its address so it stops changing. On Windows, check Use Printer Offline isn't ticked under Printers and scanners while you're there.