I have both a question and a solution - just posting this to help others. I found many, many threads on these forums from users that installed a new WiFi router and immediately starting getting 79 Service Error and the printer was cycling power.
I had this same issue. If I unplugged the new router and powered up the printer, I would have ZERO issues so I knew it was WiFi related. I tried several of the suggestions including turning off IPV6 and nothing worked.
My only successful workaround (since my printer is not near my router) was to install a small WiFi to Ethernet adapter and plug a cable into the Ethernet port of the printer. Not the ideal solution but better than replacing a printer that's only five years old.
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