1. Check your internet connection. You will need to be connected to 3G/4G or Wi-Fi to unlock your door from your smartphone (don't worry about much data usage though - its so small, only about 10 bytes - an average email is about 75 Kilobytes).
2. Check if you have enabled the use of the Digital Keys app in your Mobile data settings on your phone.
3.Ensure you touch the circle/NB IoT logo on the lock cover (LDK400) or touch star '*' button on numberpad (LDK100)to wake up the lock/so the lock knows someone is at the door to unlock the door. You must do this everytime you want to unlock the door. This is also explained in the app commentary.
3. Please try again 2-4 times - sometimes the local Wi-Fi network or the local 3G/4G network can be congested.
4. Sometimes the lock can become disconnected from the NB IoT network (e.g if maintenance is happening on the network or its congested, the lock can become disconnected). You will know the lock has become disconnected if you press the touch button and the LED light starts flashing, and the lock does not unlock. If this happens simply do a long hold down on the wake-up button (around 10 seconds) and this will reboot the device and re-connect it to the network. It should take around 30 seconds to one minute for the lock to re-connect, so you can continue to use the lock as normal.