Minimal Mongoose SSL connection code

I need to get a MongoDB connection to Node.js with Mongoose and Express to connect with SSL, but I can't connect even after knowing the keys work by connecting with Robomongo.

'use strict';

var mongoose = require('mongoose'),
    fs = require('fs'),
    express = require('express');

mongoose.set('debug', true);

// Bootstrap db connection
var db = mongoose.connect('mongodb://localhost/test', {
        options: {
            ssl: true,
            port: 27017,
            user: 'xxxxxxxx',
            pass: 'xxxxxxxx_',
            sslValidate: false,
            checkServerIdentity: false,
            sslCA: fs.readFileSync('./config/sslcerts/mongodb.pem'),
            sslCert: fs.readFileSync('./config/sslcerts/mongodb-cert.crt'),
            sslKey: fs.readFileSync('./config/sslcerts/mongodb-cert.key'),
            sslPass: 'xxxxxx'
        },
    },
    function(err) {
        console.error('Could not connect to MongoDB!');
        console.log(err);
    });

// Init the express application
var app = require('express')(db);

app.listen(8443);
console.log('MEAN.JS application started on port ' + 8443);

Here is how I fire mongod:

$ mongod --fork --logpath mongodblogs/mongodb.log --dbpath mongodb --bind_ip 127.0.0.1 --sslMode requireSSL --sslPEMKeyFile /app/website/config/sslcerts/mongodb.pem --sslCAFile /app/website/config/sslcerts/mongodb-cert.crt -v

Errors:

Could not connect to MongoDB! MongoError: connection 0 to localhost:27017 closed

same code, sometimes with another different error:

Could not connect to MongoDB! MongoError: read ECONNRESET

Mongoose version: "raw": "mongoose@4.10.8", Node version 4.8.0

Can someone help?