Some Xiaomi phones do not provide mobile data when connected to Carsifi WIFI(during Wireless Android Auto session). There are some approaches how to solve it:

1. Open WIFI settings:

  • Wi-Fi assistant -> Select best networks automatically:
    • Select best networks automatically-> on
    • Enable prompt -> on

2. Developer options. If you don't see Developer options please tap 10 times on the Version row in Settings->About 

  • Wi-Fi scan throttling -> on
  • Mobile data always active -> on
  • Use tethering hardware acceleration -> on

3. Other:

  • Disabled miui optimization in the developer options. 
  • When connected to Carsifi, accept a prompt to use mobile data.