Thanks for the suggestion. I've seen the alarm light flash 21 times, turned off the router and back on again, tried the Canon connection routine and we still have the same result. No connection.
Don't keep turning the router on and off, it isn't necessary and will only incur the wrath of DLM.
Have you tried connecting manually be entering the wireless passkey on the printer rather than using WPS?
You could also try temporarily turning off the 5Ghz wifi on the hub until the printer connects and then turn it back on again.
Who or what is DLM?
Not sure how I would enter the passkey manually on the printer as it doesn't have a keypad.
Tried turning off the 5Ghz on the router, again without success.
I've now sorted this problem via a call to Canon support.
Confession time:- Previously I made the error of pressing and holding the WPS button on the router for too long, until the large blue light at top and bottom of the circle started flashing. I have now learned that it is only necessary to press the WPS button until the blue light at the back of the router starts to flash.
Apologies for wasting people's time but maybe this will help someone else to avoid making the same mistake.
Glad you got it sorted and thanks for the update.
DLM is Dynamic Line Management, an automatic system that detects line faults and tries to keep a line stable by reducing the broadband speed. Multiple restarts of the router are misconstrued as line drops.