"no airprint printers found"

No idea what happened here.

• The Canon MF264dw was printing fine from his iPhone using Canon for Business print service from the app store. But then now Canon print service reports "no compatible printers found" even after manually keying in the correct IP address of the printer on the LAN. Android devices then had the same issue using Canon print service "no supported printers found" but the Android "default print service" is working just fine. No change from PC, still printing fine with no change.

We try to use airprint, as this is an airprint compatible printer but iOS reports "No airprint printers found"

The printer is functioning fine, connected to the same network, and is printing from PC and Android. The iPhone is on the same network, verfied by both scanning the LAN from the iPhone and seeing the printer and by logging into the printer's internal web server with safari http://192.168.0.7

Why can't airprint find the printer when it's right there on the same network?

It's a private network and all wireless access points to it have security/passkey enabled.