I have a sunroom that I added on to the house a few years ago that is the furthest from my wifi router. While my WiFi only iPad Air gets decent signal in that room, my iPhone 5C defaults to cellular data when in that room, even with WiFi turned on. Is the wifi antenna in the phone weaker because Apple knows you also have a data plan with your phone so they made it weaker or is it because the wifi antenna is smaller due to the size difference between a phone and iPad Air? I'd rather not be using precious cellular data when I'm in my own home. I even moved my router closer to the room and it still doesn't get a good signal.