how to change preferred network type over adb android? Ask Question Asked 5 years, 3 months ago. ... Marshmallow - change preferred network mode LTE/GSM. You may want to change preferred network type on your Android device either because the network speed is too fast or too slow.. If your network speed is slow even while you are in a location with a 3G or 4G signal, then it’s probably 2G that is selected as your preferred network type.