Why can't the mobile phone use 4g suddenly? What happened?

If your mobile phone can't use 4G network or the status bar network doesn't display 4G signal, it may be caused by SIM card problem, operator problem, mobile phone case problem and mobile phone setting problem. (Note: If only the secondary card has no 4G signal, it may be that your model does not support 4G of the secondary card. If dual 4G is supported, please slide under the desktop to enter the search interface, search and click Dual Card Management to enter the settings page and turn on Dual Card 4G. If the problem still exists, you can check it according to the following methods. )

SIM card problem

If your SIM card is cut, expired, and the 4G service and special SIM card are not enabled, your mobile phone may not be able to use the 4G network or display 4G signals.

Solution:

If it is card cutting, please replace the standard SIM card.

If the mobile phone card is in arrears, please pay before using it.

If the 4G service is not enabled on the mobile phone card, please replace the 4G card supporting the 4G network and ensure that the 4G service is enabled. Please consult the operator for details.

If it is a special SIM card, we have found some mobile cards that can only be used for surfing the Internet, and there are some restrictions on the use of 4G. For example, a mobile card of China Unicom needs to be manually modified before it can be used, and a mobile card of China Telecom can only be used on the mobile phone where the card is inserted for the first time, but it cannot be used when the mobile phone is changed. For the use of special mobile cards, please consult the operator about how to use them.

Operator problem

If you use a mobile phone customized by the operator and there is no local 4G network, your mobile phone may not be able to use 4G network or display 4G signals.

Solution:

If you use a mobile phone customized by an operator, some mobile phones can only use the SIM card of the corresponding operator. For example, some customized telecom versions only support using telecom cards to use telecom 4G, while using Unicom cards cannot use Unicom 4G. Please use the calling card of the corresponding operator at this time.

If there is no local 4G network, please consult the operator for details.

Mobile phone case problem

If the mobile phone is protected by a metal case, because the metal can shield the signal, it may interfere with the signal, so that the mobile phone cannot use the 4G network or display the 4G signal.

Solution:

Please take off the metal protective sleeve and try again. If the signal returns to normal, I suggest you change a protective cover.

Mobile phone setting problem

If you make a mistake in the settings of your mobile phone, it may interfere with the signal, so that your mobile phone cannot use the 4G network or display the 4G signal.

Solution:

It is recommended that you restart your mobile phone, pull down the notification panel, press and hold the mobile data to enter the mobile network interface, and turn on and enable 4G (some mobile customized models do not have 4G switch, and the system turns on 4G by default) to ensure that the 4G switch of your mobile phone is turned on.

In the mobile network interface, click the name of the access point (APN), then click the upper right corner, and select Reset to Default Settings.

Search in Settings and enter Restore Network Settings to restore the network settings of the SIM card. (Note: This step will clear the WLAN account and password previously connected to the mobile phone, and you can use the cloud service for backup. )

If there is still no 4G signal after the above steps, it is recommended that you conduct a comparative test:

Plug someone else's 4G card from the same operator into your mobile phone to see if there is a 4G signal. If there is 4G, I suggest you contact the operator to see if it is a SIM card problem.

Put your card on other mobile phones. If the 4G network cannot be used normally, please consult the operator.

If someone else's card doesn't have a 4G signal on your mobile phone or your card can normally use 4G on other mobile phones, please back up important data in advance and take the purchase invoice to Huawei customer service center for testing and processing.