I suggest you change your mobile phone and test your Unicom card. If it still doesn't work, it doesn't rule out that the mobile phone card is faulty. If the card is cut, it may also cause damage to the mobile phone card and affect the use. In this case, it is recommended that you bring your valid certificate to China Unicom's own business hall to change your card. If your mobile phone card can be used normally, there may be something wrong with the network settings of your mobile phone. I suggest you restore the mobile phone network; And you need to make sure that your mobile phone can support Unicom's network standard and network frequency.

If you use Unicom's 3G card, you can set it according to the following parameters: APN:3G net；; ; User name and password: empty; Gateway and proxy address:10.0.0.172; Gateway and proxy port number: 80.

I suggest you check your mobile phone balance. If the balance is insufficient, it may affect your use. If you owe money, it will take 48 hours to recharge the Internet.

If you are in a weak area covered by Unicom signal, it may affect your use.

If it is not for the above reasons, I suggest you take your mobile phone and mobile phone card to Unicom's own business hall or mobile phone after-sales center to help you test it.