You may need to update the firmware on your MHD UNI Wi-Fi adapter to support the G-Series unlock.
Here is the official guide on how to update the MHD UNI adapter firmware:
Install the MHD F/G app (must be F/G even if your car is E-series)
Login/register to your MHD account
In the main menu, press Get Support Files.
Without closing the app, connect to the adapter's WIFI
Click on “Codes” at the bottom right corner
Click “Read DEM fault codes”
The adapter will be updated
Wait 30 seconds, unplug and reconnect the adapter