I am experiencing this problem since I bought my lumia (820).The current setting (base on my observation), only allows my phone to connect to the strongest signal. My setting is 3g but it kept bouncing to 2g (E) even when 3g signal is available in the my area I hope microsoft would make an update that would allow us to choose between 3G only, 2g or 3g(preferred), 2g only, 4g only, and etc or like on android: gsm only, wcdma only, or the two combined with higher priority for one of the signals.