IPhone 4s keep discconecting from wifi to 3G whenever screen is locked
Hi,
My iPhone 4s keeps disconnecting from my wifi and goes to 3G everytine the screen is locked.
I noticed this problem yesterday.
I searched and googled but no luck. Someone mentioned that he/she had the same problem but managed to find the solution.
https://discussions.apple.com/thread/3650053?start=0&tstart=0
I tried that one but it only applies to 3rd party routers, i have airport extreme 4th generation as my base station, and airport express 1st generation as wired extender.
All my other devices are fine, wife's iPhone 3G, both iPad 23G and wifi.
Only my iPhone 4s
All firmwares are up to date on all appale devices that i have.
Any help!!!!!
iPhone 4S, iOS 5.1, 16GB