If you get "Security check failed..." or "To add this accessory to your home, connect your iPhone to your HomeKit enabled router..." when you pair your HomeKit accessory, please do as follows:

a. Login Wi-Fi router to check the Wireless security. If WPA3 standard ONLY is applied, please set the encryption method to Auto Mode or WPA2/WPA3 Transition for better compatibility.

b. Follow user manual to reset the accessory.

c. Power cycle the accessory. For light switch, please reboot it at the circuit breaker.

d. Configure the accessory again.