I am having the same problem. I received a new airave a few months ago. The last airave I had worked find except for power issues. However, this airave is a bit weird.
If I turn off my phone and turn it back on, my phone detects the nearest sprint tower instead of the airave downstairs. Also when I arrive home my iphone 5 refuses to detect the airave automatically like on my last airave.
This results in my having to place my phone on top of the airave for a few minutes and then it detects it. (Then later on it disconnects after a few hours)
Please help!