All smart plugs generally have same method of connecting to Wi-Fi and with the mobile application.

It's like

  1. Check the Wi-Fi light on device
  2. Search for device's Wi-Fi broadcast and connect
  3. Add home Wi-Fi SSID/password in the app
  4. Control the device with app.

So do the device is actually connected with app initially ? Whats happening while we select the device Wi-Fi broadcast ? And How the device got the Wi-Fi info (that we entered in app) is available to app?

So between step 2 and 3 device is not connected to home Wi-Fi. So the app sends the Wi-Fi info to device? What protocol is used for that?

2 Answers 2


There is no specific protocol. It's all Wi-Fi. Your smartphone connects to a temporary access point of the smart plug which is set up after you press the button. After transmitting the credentials of your home Wi-Fi via the temporary access point Wi-Fi the smart plug connects to your home Wi-Fi and you switch your smart device back as well.

That is the OSI layer story up to layer 4. What happens above that layer might be smart plug specific but it's likely a single message transmitting your home Wi-Fi credentials (hopefully encrypted). I would not consider such single messages a protocol.

  • Humm, that makes more sense that the IOT is the "hot-spot". While the phone can be a "hot-spot", I am not sure a phone will give permission to an App to become a "hot-spot".
    – st2000
    Jan 6, 2019 at 13:19
  • I want to know how does the device takes the SSID and PASSWORD only. And in what format the data is sent to the device through mobile and how the device receives it at their end and process it. Because When I searched I got to know that via OTA(But have to create a new sketch and convert it to .bin file and then upload it into the device) but this will be very complicated for mobile apps.
    – Lucifer
    Feb 25, 2020 at 7:41

This is speculation, so any comments to improve this answer will be appreciated.

Likely most IOT devices expect you to download their App into a modern smart phone. That the App temporarily turns the smart phone into a wifi hot-spot with a specific SSID which will accept a connection from the IOT device. Configuration data for the wifi network normally used it sent. The phone returns to the normal wifi network as does the IOT device.

  • i think this is backwards: the new device is an AP, which the phone connects to and transmits the SSID+PW of the local wifi WAN, at which point the device reboots and joins the wifi.
    – dandavis
    Jan 8, 2019 at 22:10
  • Yes, I agree. I think the other answer makes more sense.
    – st2000
    Jan 9, 2019 at 1:03

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.