If you get the error "mi home failed to initialize device (3) " in your MiHome app (for me it was on iOS):
Steps to fix (hope one of this step will help you):
- check if you have a connection to the Internet (try to open any page in the browser)
- check if you have NO problems with available memory space on your device (for me deleting few apps and emptying ~250mb instead of 14mb helped to solve the issue)
- try to reinstall the app
- try to reboot the GateWay
- check that the device is running (reset power on it = reboot)
- try to ask for help on MiHome Forum
- ...
- God bless you!