Problem with http requests

Ionic Framework ionic-v3
1

Hello,

I am having problem with http requests in my app. I am using code from tutorial so it looks like this:

this.http.post(url, JSON.stringify(data), {
  headers: headers
})
  .subscribe(data => {
    console.log(data);
  }, error => {
    console.log(error);
  });

The link is to my server side, where it should save data from this post, but when I perform action with my post request, the server respond with:

net::ERR_CONNECTION_REFUSED

I do not know where is the problem, I have whitelist installed and also config.xml updated.