ESPAsyncWiFiManager/examples/AutoConnectWithTimeout/AutoConnectWithTimeout.ino

#if defined(ESP8266)
#include <ESP8266WiFi.h>          //https://github.com/esp8266/Arduino
#else
#include <WiFi.h>
#endif

//needed for library
#include <ESPAsyncDNSServer.h>           //https://github.com/devyte/ESPAsyncDNSServer
                                         //https://github.com/me-no-dev/ESPAsyncUDP
#include <ESPAsyncWebServer.h>
#include <ESPAsyncWiFiManager.h>         //https://github.com/tzapu/WiFiManager

AsyncWebServer server(80);
AsyncDNSServer dns;



void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);

  //WiFiManager
  //Local intialization. Once its business is done, there is no need to keep it around
  AsyncWiFiManager wifiManager(&server,&dns);
  //reset settings - for testing
  //wifiManager.resetSettings();

  //sets timeout until configuration portal gets turned off
  //useful to make it all retry or go to sleep
  //in seconds
  wifiManager.setTimeout(180);

  //fetches ssid and pass and tries to connect
  //if it does not connect it starts an access point with the specified name
  //here  "AutoConnectAP"
  //and goes into a blocking loop awaiting configuration
  if(!wifiManager.autoConnect("AutoConnectAP")) {
    Serial.println("failed to connect and hit timeout");
    delay(3000);
    //reset and try again, or maybe put it to deep sleep
    ESP.reset();
    delay(5000);
  }

  //if you get here you have connected to the WiFi
  Serial.println("connected...yeey :)");

}

void loop() {
  // put your main code here, to run repeatedly:

}