Socket.io Not working in live server Ubuntu

Hi

Am trying with socket.io and I made successful run on localhost. But when I tried to implement the same on server it doesn't work.

Server Code
var server = require('http').Server();

var io = require('socket.io')(server);


server.listen(4000, '0.0.0.0', function () {
    console.log('listening');
});

io.on('connection', function(socket) {

    console.log('Client connected.');

    // Disconnect listener
    socket.on('disconnect', function() {
        console.log('Client disconnected.');
    });
});


Client Code

<script src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/2.0.4/socket.io.js"></script>
<script>
//for localmachine
    var socket = io.connect(':4000');
//for server
var socket = io.connect(':4000');
    console.log(socket.connected);
    console.log(socket.connecting);
    socket.on( 'connection', function () {
        console.log( 'connected to server' );
    } );

    console.log(socket);
    socket.on('connect_error', handleNoConnect);
    socket.on('connect_timeout', handleNoConnect);
    socket.on('connect', onConnect);

    function handleNoConnect() {
        console.log("No connection");
    }

    function onConnect() {
        console.log("connected");

// set other event handlers on a connected socket
        socket.on('disconnect', function() {
            console.log("disconnected");
        });
    }

    socket.on('connection',function (data) {
        console.log(data);
    });
</script>

Though I checked the 4000 port is listening in IPV4

COMMAND  PID       USER   FD   TYPE  DEVICE SIZE/OFF NODE NAME
node    9899 buffercode   12u  IPv4 3246821      0t0  TCP *:4000 (LISTEN)

Am getting No Connection.

Kindly suggest me where I did the mistake