As i know you can't control from which tray you want to print from you mobile so what is the default tray on the printer the iPhone will send the job to it and the tray priority is the reference when you want to print standard sizes
so make sure about the settings from you iPhone if it print letter or A4 also if it LEF or SEF
I have just installed this printer at home. AirPrint works fine. However I cannot get it to print from tray 1. It is loaded with about 50 sheets of A4 with guide rails all correctly set I think. Just get message “paper mismatch tray 1”. What is wrong here? Thank you!