Suggestion:
1. Check whether the card has traffic, check whether the card status can be used normally, and refresh the card;
2. Reset the device and add it again; Pay attention to listening to the voice broadcast of the device when it is turned on, whether it can broadcast [network connection successfully] normally;
3. If the device cannot be turned on and cannot broadcast [Network Connection Successful], it is likely to be a card status problem; There is no traffic on the SIM card, or the SIM card is abnormal, or the SIM card cannot access the Internet normally; Please try to change the SIM card;