Hello I have a Huawei P8 and is with 2G and 3G network connection problems. It only works on 4G network. But I can not make calls and or receive calls. I can only send and receive messages. Can you tell me what to do so you can estabeler connection with the networks 2 and 3G? I've tried everything, or almost everything (including upgrading the UI to EMUI 4.0.1 and Android 6.0)