GET/ socket io not found 404

Im following the socket io documentation though still am getting an error

polling-xhr.js:157 GET http://localhost:3000/socket.io/?EIO=4&transport=polling&t=NtNlWd6 404 (Not Found)

it my be something very simple though I am stuck

below is my code

server.js

const express = require('express'); //Line 1
const app = express(); //Line 2
const port = process.env.PORT || 5000; //Line 3


const http = require('http').Server(app);

const io = require('socket.io')(http);



//Whenever someone connects this gets executed
io.on('connection', function(socket) {
    console.log('A user connected');
 
    //Whenever someone disconnects this piece of code executed
    socket.on('disconnect', function () {
       console.log('A user disconnected');
    });
 });



// This displays message that the server is running and listening to specified port
app.listen(port, () => console.log(`Listening on port ${port}`)); //Line 6

// create a GET route
app.get('/express_backend', (req, res) => { //Line 9
    console.log("printing from the server f3f134g")
  res.send({ express: "YOUR EXPRESS BACKEND IS CONNECTED TO REACT" }); //Line 10
}); //Line 11

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <link rel="icon" href="%PUBLIC_URL%/favicon.ico" />
    <meta
      name="viewport"
      content="width=device-width, initial-scale=1"
    />
    <meta name="theme-color" content="#000000" />
    <meta
      name="description"
      content="Web site created using create-react-app"
    />
    <link
      rel="apple-touch-icon"
      href="%PUBLIC_URL%/logo192.png"
    />
   
  </head>
  <body>
    
    <script src="https://cdn.socket.io/4.4.0/socket.io.min.js" integrity="sha384-1fOn6VtTq3PWwfsOrk45LnYcGosJwzMHv+Xh/Jx5303FVOXzEnw0EpLv30mtjmlj" crossorigin="anonymous"></script>
    
<script>
  var socket = io();
</script>

    <div id="root"></div>
  
  </body>
</html>

please note both

```<script src="/socket.io/socket.io.js"></script>```

and

    <script src="https://cdn.socket.io/4.4.0/socket.io.min.js" integrity="sha384-1fOn6VtTq3PWwfsOrk45LnYcGosJwzMHv+Xh/Jx5303FVOXzEnw0EpLv30mtjmlj" crossorigin="anonymous"></script>

give an error