Arduino Ethernet Web Server Receiving Client Requests But Not Doing Anything

I started playing around with my Arduino and an Ethernet Shield, trying to get an LED to turn on or off when specific HTTP requests are made. I forwarded port 80 on my router and sent the links to turn on or off the LED to my friends. The sketch worked on my side, but nobody else's. The sketch even worked for me when I used both my private and public IP addresses in the link. I even saw TX and RX flashing when people clicked the links, but no action in the LED or Serial Monitor. It's possible I port forwarded wrong, but has anyone else had this problem or knew of a way to fix it if in the event I didn't port forward incorrectly?

It may be your ISP blocks port 80 requests to residential ip addresses. Mine does.

Using a different port may help, like 8080.

You can try to telnet to the port to see if you can establish a connection. If you can then the port is not blocked. If you can not, then you have an idea where to look.

It may be your ISP blocks port 80 requests to residential ip addresses. Mine does.

Using a different port may help, like 8080.

That seems fairly plausible. I will try this in the morning :slight_smile:

Simple server control test cide.

//zoomkat 4-1-12
//simple button GET for servo and pin 5
//for use with IDE 1.0
//open serial monitor to see what the arduino receives
//use the \ slash to escape the " in the html, or use ' instead of " 
//address will look like when submited
//for use with W5100 based ethernet shields

#include <SPI.h>
#include <Ethernet.h>

#include <Servo.h> 
Servo myservo;  // create servo object to control a servo 

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED }; //physical mac address
byte ip[] = { 192, 168, 1, 102 }; // ip in lan
byte gateway[] = { 192, 168, 1, 1 }; // internet access via router
byte subnet[] = { 255, 255, 255, 0 }; //subnet mask
EthernetServer server(84); //server port

String readString; 


void setup(){

  pinMode(5, OUTPUT); //pin selected to control
  //start Ethernet
  Ethernet.begin(mac, ip, gateway, gateway, subnet);

  myservo.write(90); //set initial servo position if desired
  myservo.attach(7);  //the pin for the servo control
  //enable serial data print 
  Serial.println("server servo/pin 5 test 1.0"); // so I can keep track of what is loaded

void loop(){
  // Create a client connection
  EthernetClient client = server.available();
  if (client) {
    while (client.connected()) {
      if (client.available()) {
        char c =;

        //read char by char HTTP request
        if (readString.length() < 100) {

          //store characters to string 
          readString += c; 

        //if HTTP request has ended
        if (c == '\n') {

          Serial.println(readString); //print to serial monitor for debuging 

          client.println("HTTP/1.1 200 OK"); //send new page
          client.println("Content-Type: text/html");

          client.println("<TITLE>Arduino GET test page</TITLE>");

          client.println("<H1>Zoomkat's simple Arduino button</H1>");
          client.println("<a href='/?on'>ON</a>"); 
          client.println("<a href='/?off'>OFF</a>"); 

          //stopping client

          ///////////////////// control arduino pin
          if(readString.indexOf("on") >0)//checks for on
            digitalWrite(5, HIGH);    // set pin 4 high
            Serial.println("Led On");
          if(readString.indexOf("off") >0)//checks for off
            digitalWrite(5, LOW);    // set pin 4 low
            Serial.println("Led Off");
          //clearing string for next read