I have tried a loot of ways to get my Dell C1765nfw to print from my iPhone, unfortunately it is not AirPrint compatible.
Rather by accident, I still have Netgear’s Genie program installed on an old Windows 7 installation (from the time bedore I had a Fritz!Box), and just noticed by accident that it comes with an AirPrint functionality, which also works if your router isn’t a Netgear one.