I have sonoff device used to on/off the light. I have installed and configured it through ewelink. All works fine .i just want to know how the cloud server is able to reach my sonoff device over internet although it doesn't have a public IP? I understand that the sonoff device is using http post and get requests to reach the server for status update and query as the server has public ip..etc. but don't understand how the cloud server is sending commands (on/off) to the sonoff device despit it doesn't have a public ip? So how the server is reaching the device over internet?