Problem: When the Blackview BV900 Pro has connected to a Wifi network, once the phone goes out of range (ie. leave the house or office), the phone is unable to connect to the internet via 3G/4G, even when the 3G/4G icons are displayed without the "x" sign in them

Environment: Build number BV9000Pro_Blackview-V1.1_20171215

Severity: High

Steps to reproduce
1. Bring phone to a location where it has access to a Wifi access point. It will connect to Wifi and work properly.
2. Walk away from the Wifi access point and let the phone disconnect from wifi and go back to 3G/4G

Expected results: Phone should automatically change internet source from Wifi to 3G/4G
Actual results: Phone shows 3G/4G as connected, but no internet data is coming into the phone

please try to update to the latest ROM
you can find it in here:
viewtopic.php?f=213&t=341480

here is the guide link to help you:
viewtopic.php?f=192&t=334922