When I go to print from my iPhone or iPad, it says “no air printers found”. Two days ago, I had no issues. I have rebooted all devices. They are all on the same network. I have no issues with my PC recognizing the printer. Can you advise?

Does your Printer supports AirPrint?

Read here => Use AirPrint to print from your iPhone, iPad, or iPod touch - Apple Support

See Printer list => About AirPrint - Apple Support

If you have a WiFi extender, make sure it isn't interfering with your air printer connection. I have seen that happen. Short of that, I'm not sure what has happened. If no one else hits you with a different solution, you can always reset your network settings via:

Settings-->General-->Reset-->Reset Network Settings: 

All network settings will be removed. In addition, the device name assigned in "About" is reset to “iPhone,” and manually trusted certificates (for websites etc) are changed to untrusted. You'll need to re-enter passwords for WiFi etc.

***Make sure you select the correct reset option! Don't accidentally reset all content and settings, which is essentially a factory reset of the device.

***Consider doing a device backup in iCloud before doing the reset (for your own peace of mind).

~( ):>