Can't print using AirPrint - iOS 8.3 to Canon MX535

Hi,

AirPrint stopped working some weeks ago from our I phones 5, 6 and i pad air 2 to our Canon Pixma MX535. I've been on the phone to Canon who say this is an iOS issue, the printer is connected to the wifi network and I can print from the Mac.

The devices are all on iOS 8.3

The firmware is up to date on the printer and I can view the printer at our IP address.

I have reset the router, the printer and the iPad (several times).

I've reinstalled the printer software.

Does anyone have any suggestions? TIA