You said it was a Canon printer, is it a Pixma by any chance?
Yes
There's your problem . . . .
Cheap though.
The problem is that it needs it's IP memory purged.
Remove the paper from the tray and place the printer in a warm bath with a tablespoon of washing up liquid.
Leave it for 30 minutes to ensure all the corrupt data has been removed, then remove and place on a pile of newspapers for an hour.
Re-load the paper and switch on. You will find you can no longer print a test page with WIFI or cable.
Job done.