You can troubleshoot in the following ways:

• Check the Internet connection of the home Wi-Fi.
• Make sure your home Wi-Fi password has not been changed.
• Do not use a metal faceplate on the wall switch, as that will reduce the Wi-Fi signal.
• Restart the switch by pressing the restart button.
• If all other methods fail, press and hold the power button for 5 seconds to restore factory settings, and then try to add again.