esp8266 webserver with wifimanager Async using https://github.com/alanswx/ESPAsyncWiFiManager repository

here is the schematics of the board that i used

i used D4(GPIO2) , D3(GPIO0) , D2(GPIO4) and 3V pins for this module

1. D4 -> red
2. D3 -> green
3. D2 -> blue

first time that you upload the code using Arduino IDE v2.x.x
you get esp_wifi as AccessPoint(no password) then Enter 192.168.4.1
(be carefull not to use https instead of http).
whenever you use disconnect button in the page you will get an AP named esp_wifi again,
then you can enter your new credentials, after that the board restarts and connects to new wifi. note that your old credentials will be erased each time for the
WiFi.disconnect(true,true); in testasync.ino file.

for finding the IP of board for the main webpage you can check your router or alternativly you can use ip neigh command in linux or
termux(android terminal emulator) for finding the IP.
(be carefull not to use https instead of http).

to prevent the board from erasing the the credentials change the
WiFi.disconnect(true,true); to
WiFi.disconnect(true,false); in the testasync.ino file.

turning the builtin LED would turn on the the Red LED on RGB module