For the issue you have , please try as below :

We suggest you reset your device by holding the reset button and restart the setup procedure. Before this, please make sure:

1.Ensure that your Micro SIM card is on our compatible list. You may check the information on https://www.ezviz.com/inter/product/EB8/46565#Carrier

2.Ensure that the SIM card PIN is unlocked before being insert into the device.

3.If the device still prompts “Connection failed”, tap “Try APN Configuration” in the app interface and follow the app wizard to finish the APN Configuration. For APN information, please liaise with your carrier.

Data usage of the EB8 4G depends on the bitrate you set up. One hour of live feed in 1080P mode (default bitrate: 1Mbps) will use about 0.4GB of data. Based on that, you can estimate the data usage to choose the right data plan for you.