Can't connect to a node.js server on my VPS

Well, I hope this question isn't silly or repeated. I promise I have researched and tested a lot.

I've have a server on my VPS with this code:

var app = require('express')();
var server = require('http').Server(app);
var io = require('socket.io')(server);

server.listen(8080);

io.on('connection', function(socket) {
  socket.on('hello', function() {
    console.log('Hello received');
  }
}

And a client in another machine:

<script>
  var socket = io.connect('http://[VPS Public IP]:8080');
  io.emit('hello');
</script>

This works when using private IP addresses and the same net. When using public IP this doesn't work. Any idea of why is this happening?

Thank you.

via A. Alcazar