Redmi 2a mobile phone was disconnected when receiving SMS after upgrading miui8.

It is suggested to check the cause and solve it as follows:

1. Check whether the mobile phone is in arrears. The overdue mobile phone can't connect to the data network and needs to be recharged.

2. If the refresh fails due to network delay, you can turn on the flight mode of the mobile phone, turn it off after five seconds, and then reconnect the network or restart the mobile phone.

3. If the network settings are incorrect, you can call the operator to which the mobile phone card belongs, and ask the customer service to send the relevant data of the internet settings and make the settings according to the prompts.

4. If you are connected to a wireless network, you need to check whether the wifi password input of the mobile phone and the Internet access settings of the wireless router are correct, and whether other devices can access the Internet through this wifi. It is suggested to delete the mobile phone wifi password and re-enter it, or restart and reset the wireless router.