I am trying to reach the webserver running in my Wemos D1 Mini compatible board.

I am trying one esp8266 example using Arduino examples "WifiManualServer" code below. I have replaced the SSI and password for my wifi network in the lines

#define STASSID "my wifi ssid"
#define STAPSK  "my secret"
    This sketch demonstrates how to set up a simple HTTP-like server.
    The server will set a GPIO pin depending on the request
      http://server_ip/gpio/0 will set the GPIO2 low,
      http://server_ip/gpio/1 will set the GPIO2 high
    server_ip is the IP address of the ESP8266 module, will be
    printed to Serial when the module is connected.

#include <ESP8266WiFi.h>

#ifndef STASSID
#define STASSID "my wifi ssid"
#define STAPSK  "my secret"

const char* ssid = STASSID;
const char* password = STAPSK;

// Create an instance of the server
// specify the port to listen on as an argument
WiFiServer server(80);

void setup() {

  // prepare LED
  digitalWrite(LED_BUILTIN, 0);

  // Connect to WiFi network
  Serial.print(F("Connecting to "));

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
  Serial.println(F("WiFi connected"));

  // Start the server
  Serial.println(F("Server started"));

  // Print the IP address
  server = WiFiServer(80);

void loop() {
  // Check if a client has connected
  WiFiClient client = server.available();
  if (!client) {
  Serial.println(F("new client"));

  client.setTimeout(5000); // default is 1000

  // Read the first line of the request
  String req = client.readStringUntil('\r');
  Serial.println(F("request: "));

  // Match the request
  int val;
  if (req.indexOf(F("/gpio/0")) != -1) {
    val = 0;
  } else if (req.indexOf(F("/gpio/1")) != -1) {
    val = 1;
  } else {
    Serial.println(F("invalid request"));
    val = digitalRead(LED_BUILTIN);

  // Set LED according to the request
  digitalWrite(LED_BUILTIN, val);

  // read/ignore the rest of the request
  // do not client.flush(): it is for output only, see below
  while (client.available()) {
    // byte by byte is not very efficient

  // Send the response to the client
  // it is OK for multiple small client.print/write,
  // because nagle algorithm will group them into one single packet
  client.print(F("HTTP/1.1 200 OK\r\nContent-Type: text/html\r\n\r\n<!DOCTYPE HTML>\r\n<html>\r\nGPIO is now "));
  client.print((val) ? F("high") : F("low"));
  client.print(F("<br><br>Click <a href='http://"));
  client.print(F("/gpio/1'>here</a> to switch LED GPIO on, or <a href='http://"));
  client.print(F("/gpio/0'>here</a> to switch LED GPIO off.</html>"));

  // The client will actually be *flushed* then disconnected
  // when the function returns and 'client' object is destroyed (out-of-scope)
  // flush = ensure written data are received by the other side
  Serial.println(F("Disconnecting from client"));

Once I compile and upload the sketch, the sketch is able to connect to my wifi network. The following is the output in the serial monitor.

20:45:12.633 -> Connecting to <text replaced xxxxxxx>
20:45:13.247 -> ........
20:45:17.551 -> WiFi connected
20:45:17.551 -> Server started
20:45:17.551 ->

I am able to verify the client connection in my wifi routers network management UI. The espboard is connected and assigned the IP as in the output (

When I launch browser and try to get, the request times out. from my windows 10 pc, tried ping on, the Request timed out.

From the sketch I see the following lines in the loop() function:

  WiFiClient client = server.available();
  if (!client) {
  Serial.println(F("new client"));

The execution never reached the line Serial.println(F("new client"));.

I had tried inserting the line server = WiFiServer(80); after the wifi connection is established.

Please share your thoughts on why the server.available() is not successful?

  • Is your windows 10 PC on the same subnet? Does your WiFi router impose WiFi Isolation?
    – Majenko
    Commented May 16, 2021 at 10:59
  • 1
    remove the line server = WiFiServer(80);
    – Juraj
    Commented May 16, 2021 at 11:28
  • I think you have to call server.on() somewhere so the server does actually serve an url. Which library do you use btw (there is nothing behind #include for me)?
    – Sim Son
    Commented May 16, 2021 at 12:12
  • @SimSon, this is not ESP8266WebServer library
    – Juraj
    Commented May 16, 2021 at 14:48
  • @Juraj, thanks for the suggestion. I have now removed the line server = WiFiServer(80). The issue is resovled. The server is now reachable. Thanks your help. Commented May 17, 2021 at 7:46


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