Hello
Sounds like Canon support is not very competent here.
This model doesn't support 5Ghz wifi, If you recently switch ISP and get on a new router, chance is, your router might be set to broadcast 5G only. Can you confirm that? If that's the case, you need to create another SSID/channel to have the router also broadcast at 2.4Ghz, and see if the printer connects. This is the most likely/most common cause to scenario where users upgrade router or switch ISP.