Wifi networking with ESP8266 (NODEMCU version)
Here you are the working code allowing you to choose SSID, password, network name and IP address of your ESP8266 acting as an access point. In addition, you can specify wifi channel to avoid interference with other devices. A password must be at least 8 characters long or it wouldn't work.

#include &lt;ESP8266WiFi.h&gt;
#include &lt;WiFiClient.h&gt;
#include &lt;ESP8266WebServer.h&gt;

IPAddress ip(192,168,1,81);         // choose IP address
IPAddress subnet(255,255,255,0);

ESP8266WebServer server(80);

void handleRoot() {
  String page = "&lt;!DOCTYPE html&gt;\n";

  page += "&lt;html&gt;\n&lt;body&gt;\n&lt;h1&gt;Some heading&lt;/h1&gt;&lt;br&gt;Generated by ESP8266\n&lt;/body&gt;\n&lt;/html&gt;";
  server.send(200, "text/html", page);
}

// what to do when accessed through http://ip_address/something_undefined
void handleNotFound(){
  String message = "File not found\n\n";
  message += "URI: ";
  message += server.uri();
  message += "\nMethod: ";
  message += (server.method() == HTTP_GET)?"GET":"POST";
  message += "\nArguments: ";
  message += server.args();
  message += "\n";
  for (uint8_t i=0; i&lt;server.args(); i++){
    message += " " + server.argName(i) + ": " + server.arg(i) + "\n";
  }
  server.send(404, "text/plain", message);
}

void setup(void){
  Serial.begin(74880);                      // so you can see debug messages automatically sent by ESP8266
  WiFi.mode(WIFI_AP);
  WiFi.softAPConfig(ip, ip, subnet);        // declared as: bool softAPConfig (IPAddress local_ip, IPAddress gateway, IPAddress subnet)
  WiFi.softAP("SOME_NAME", "password", 7);  // network name, network password, wifi channel

  IPAddress myIP = WiFi.softAPIP();
  Serial.println();
  Serial.print("AP IP address: ");
  Serial.println(myIP);

  server.on("/", handleRoot);               // what to do when accessed through browser using http://IP_address

  // what to do when accessed through http://ip_address/test
  server.on("/test", [](){
    server.send(200, "text/plain", "This is another page");
  });

  server.onNotFound(handleNotFound);

  server.begin();
  Serial.println("HTTP server started...");
}

void loop(void){
  server.handleClient();
}


You can write something like:

server.on("/open_door", [](){
        // the code to switch on the relay to open the door
        // ... &lt;-- put here the code
        server.send(200, "text/html", "Door: opened");
});


so you can open the door with http://ip_address/open_door.

You can try http://ip_address/something_undefined?a=24&amp;b=25 to get an idea how to process the parameters.