Request for another domain?

Question

HTTP headers

How many have not encountered problems all the time and something does not work with these cross-domain requests.
This time the POST request to the server does not work.
I send a post request from the Client to the JS, on the server I registered everything that I found, namely:

header('Access-Control-Allow-Origin: *');
        header('Access-Control-Allow-Headers: Origin, Content-Type, X-Auth-Token');
        header('Access-Control-Allow-Methods: GET, POST');
        header('Access-Control-Allow-Credentials: true');

Get requests work, post does not work. The error is the following:

XMLHttpRequest cannot load https://xxx.com/app/auth. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8080' is therefore not allowed access.

What is missing? Help me please!