Red flashing light: Your hub is searching for local wifi. Follow instructions on your ilume™ app to connect all devices.
Solid white: When correctly set up the light on the hub will be solid white. It should remain solid white at all times, as the hub needs to be plugged into a power source at all times in order to sync latest data with your ilume™ app.
Solid red: This means there is a wifi connection issue. Disconnect the hub from a power source and wait a couple of seconds before plugging it back in again. If the Hub continues to show solid red light you will be able to reset all devices as described here.