NodeJs - socket.io error: xhr-polling

I have a new server configured like this:

var express  = require('express');                                                  // CHAMADA DA API EXPRESS
var app = express();
var server = require('http').createServer(app);                                     // CHAMADA DO HTTP
var io = require('socket.io').listen(server);                                       // CHAMADA DO SOCKET
var script = {};                                                                    // OBJETO
var red, blue, reset;                                                               // CORES NO CONSOLE    
    red   = '\u001b[1;31m';                                                         // VERMELHO
    blue  = '\u001b[36m';                                                           // AZUL
    reset = '\u001b[0m';                                                            // PADRAO
app.listen(8088,function(){                                                      // OUVIR NA PORTA 8088
    console.log('Express server listening on port 8088 in %s mode', app.get('env'));
});
io.sockets.on('connection', function (socket) {/*...*/});

It is in production running normally on almost all the machines that access it, but some machines get that xhr-polling loading all the time and it just does not work. I have no idea if this is a problem on the server or on the client machines, since this error only appears on a few clients.

I did this in the lab and got this log:

C:\Program Files (x86)\nodejs>node.exe socketServer.js
   info  - socket.io started
Server ouvindo a porta 8088
Express server listening on port 8088 in development mode
   debug - client authorized
   info  - handshake authorized EjVRi0UO02fwVUQZah80
   debug - setting request GET /socket.io/1/websocket/EjVRi0UO02fwVUQZah80
   debug - set heartbeat interval for client EjVRi0UO02fwVUQZah80
   debug - client authorized for
   debug - websocket writing 1::
Conexao no Socket ok
   debug - setting request GET /socket.io/1/xhr-polling/EjVRi0UO02fwVUQZah80?t=1438267327637
   debug - setting poll timeout
   debug - discarding transport
   debug - cleared heartbeat interval for client EjVRi0UO02fwVUQZah80
   debug - setting request GET /socket.io/1/jsonp-polling/EjVRi0UO02fwVUQZah80?t=1438267337643&i=0
   debug - setting poll timeout
   debug - discarding transport
   debug - clearing poll timeout
   debug - clearing poll timeout
   debug - jsonppolling writing io.j[0]("8::");
   debug - set close timeout for client EjVRi0UO02fwVUQZah80
   debug - jsonppolling closed due to exceeded duration
   debug - setting request GET /socket.io/1/jsonp-polling/EjVRi0UO02fwVUQZah80?t=1438267357677&i=0
   debug - setting poll timeout
   debug - discarding transport
   debug - cleared close timeout for client EjVRi0UO02fwVUQZah80
   debug - clearing poll timeout
   debug - jsonppolling writing io.j[0]("8::");
   debug - set close timeout for client EjVRi0UO02fwVUQZah80
   debug - jsonppolling closed due to exceeded duration
   debug - setting request GET /socket.io/1/jsonp-polling/EjVRi0UO02fwVUQZah80?t=1438267377699&i=0
   debug - setting poll timeout
   debug - discarding transport
   debug - cleared close timeout for client EjVRi0UO02fwVUQZah80