Node.JS Only works on Localhost?

var app = require('http').createServer(handler);
var Rcon = require('rcon');
var url  = require('url');

app.listen(7777);
console.log('Server started.');
function handler (req, res) {
    console.log('New connection!');
    res.writeHead(200);
    var urlParts = url.parse(req.url, true);
    var server = urlParts.query;
    var conn = new Rcon(server.ip, server.port, server.password);
    conn.on('auth', function() {
        conn.send(server.command);
        console.log('Sent command!');
    }).on('response', function(data) {
        res.end(data);
        console.log('Response: '+data);
    }).on('error', function(data) {
        res.end('error');
        console.log('Error: '+data);
    }).on('err', function(data) {
        res.end('error');
        console.log('Error: '+data);
    });
    conn.connect();
}

All of that works perfectly on localhost but when I upload to a remote server and run it, it responds with error in browser and with this in the console:

Server started. New connection! Error: TypeError: Object 0�P�q has no
method 'writeInt32LE' New connection! Error: Error: EINVAL, Invalid
argument