This example here is using a Captive Portal, for an easy connection with the single webpage application. Try it, you have only select the SSID "SleepUinoPreDev" in the WLAN list of available network on your mobile device. That’s it, now the single webpage application will start on your mobile device.
A simple interface connection for all WLAN devices, independently of the used os platform.
If you have an ESP8266 or ESP32 you can find final binaries of this sketch as example for the ESPEasyFlasher2.0.