Ever since the 4.4.4 upgrade my exchange won't stay connected to my corporate exchange server (2007). I did a factory reset and it worked for two days then stops connecting again, managed to get it to connect for a day but stopped again. WiFi is off, data sync/email sync is on, power save off, full bars and 4G LTE service (TMobile). Battery at 75%, never got below 15% since the factory reset. Frustrated because this doubles as my corporate phone. Any ideas I might be missing?