Why did I fail to set up my Onvis S4 series smart plug?

(1) Make sure Bluetooth is enabled in your iOS device.
(2) Make sure the smart plug (S4 S4EU S4UK) is within Bluetooth range of your iOS device.
(3) Make sure your Thread network is in place and working, and the smart plug is within Thread coverage.
(4) Input the correct MATTER setup code.
(5) Make sure the ecosystem app and hub supports Thread and Matter commissioning. An Android device and app are required to commission to Google, Alexa and SmartThings hubs(as of Jan 2023).