With an AirPrint-compatible printer, printing on iPad should be as easy as tapping the Share button, choosing Print, and selecting your printer. The iPad sends the print job to the printer and you should be good to go, but the process isn’t always seamless.
How to Fix “No AirPrint Printers Found” Message for iPhone and iPad | HP Support
If you're unable to print or your iPad can't find your printer, try the troubleshooting steps below to resolve common issues.
The most common problem occurs when the iPad cannot find or recognize your printer. The root cause of this problem is that the iPad and the printer are not communicating properly with each other.
Some printers, especially the first AirPrint printers, are a bit finicky and require special handling from time to time.