(1) Please confirm if your WiFi is on the 2.4GHz frequency. If you have another phone or iPad, you can try using the personal 2.4GHz hotspot of that device to test and determine if the issue is related to the network.
(2) If you are using an iPhone, unplug the device and plug it back in. Then press and hold the power button for 5 seconds to reset the HomeKit plug until the LED indicator flashes red. After that, reconnect the HomeKit plug to the Treatlife/Smart Life application.
In the Treatlife app, go to "Profile," or in the Smart Life app, go to "Me." Select "HomeKit Information" and then "Add HomeKit Device." Scan the code on the surface of the switch and wait for the connection to be successful.