Web server on NodeMCU can only be reached by one PC

Projects General Guidance
1

I have a NodeMCU running a web server - adapted from this tutorial

It sits on my network at 192.168.1.31

and produces a display in a browser window.

However when I try to access it from another PC I get

The server at 192.168.1.31 is taking too long to respond.

If I close the first window it appears on the other PC. Seems it can olnly serve one client at a tiime.

Any ideas?

2

Depending on the software implementing the server, it may not be written to support multiple client connections, or if you’re lucky, within the initialisation code there might be a value that allows you to set the maximum number of simultaneous connections.

The reason may be either be to contain memory usage, or just to simplify the server code.

3

Sorry I forgot to include the code. The ESP8266WebServer library is a total mystery to me so if it has limitations - or settings that can be changed - I'd be lost.

#include <ESP8266WebServer.h>
#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>

#define SEALEVELPRESSURE_HPA (1013.25)

Adafruit_BME280 bme;

float temperature, humidity, pressure, altitude;

/*Put your SSID & Password*/
const char* ssid = "YourNetworkName";  // Enter SSID here
const char* password = "YourPassword";  //Enter Password here

ESP8266WebServer server(80);              
 
void setup() {
  Serial.begin(115200);
  delay(100);
  
  bme.begin(0x76);   

  Serial.println("Connecting to ");
  Serial.println(ssid);

  //connect to your local wi-fi network
  WiFi.begin(ssid, password);

  //check wi-fi is connected to wi-fi network
  while (WiFi.status() != WL_CONNECTED) {
  delay(1000);
  Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected..!");
  Serial.print("Got IP: ");  Serial.println(WiFi.localIP());

  server.on("/", handle_OnConnect);
  server.onNotFound(handle_NotFound);

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

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

void handle_OnConnect() {
  temperature = bme.readTemperature();
  humidity = bme.readHumidity();
  pressure = bme.readPressure() / 100.0F;
  altitude = bme.readAltitude(SEALEVELPRESSURE_HPA);
  server.send(200, "text/html", SendHTML(temperature,humidity,pressure,altitude)); 
}

void handle_NotFound(){
  server.send(404, "text/plain", "Not found");
}
4

That's odd. Can you look at the page source on the PC and check whether there's any meta tag causing the page to be continuously refreshed?

5

Try using the async web server. It allows more than one connection at a time.

Using asynchronous network means that you can handle more than one connection at the same time

6

Its only refreshing once a second. I could easily reduce that if that is the problem.
@DaveE I have a spare ESP32 WROOM 32 DEVKIT C - I'll try the AsyncServer on that.

//AJAX code to do the refresh
  ptr += "<script>\n";
  ptr += "setInterval(loadDoc,1000);\n";
  ptr += "function loadDoc() {\n";
  ptr += "var xhttp = new XMLHttpRequest();\n";
  ptr += "xhttp.onreadystatechange = function() {\n";
  ptr += "if (this.readyState == 4 && this.status == 200) {\n";
  ptr += "document.body.innerHTML =this.responseText}\n";
  ptr += "};\n";
  ptr += "xhttp.open(\"GET\", \"/\", true);\n";
  ptr += "xhttp.send();\n";
  ptr += "}\n";
  ptr += "</script>\n";
7

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