Don't mean he have exactly same firmware or hardware type (A or B or C) as you have. He may have a bad firmware or bad hardware type.
What firmware and type your DIR-655 is?
Mine firmware 2.01NA and B1 and it is 100% stable with iPad,PS3, Macbook, Macbook Air, and Mini Mac thru wireless.
I updated it a while ago, I'll have to check it sometimes when I'm home.