Android HttpURLConnection always unauthorized 401 response (Spring Boot REST API)

Question

I am attempting to consume a REST API with an Android app I am developing in Android Studio. I have developed the API using Spring Boot.

The issue:

Whenever I make a call to my API I am always returned a 401 Unauthorized response. "Pre-authenticated entry point called. Rejecting access."

I have configured my CORS as follows:
cors: allowed-origins: "*" allowed-methods: GET, PUT, POST, DELETE, OPTIONS allowed-headers: "*" exposed-headers: allow-credentials: true max-age: 1800

My api is running on localhost:8080, and I am making the requests from my device with my WLAN IPv4 address.

Such as: curl -v -X GET http://192.168.1.xx:8080/api/users
This returns a 200 OK response.
I am also able to call this in postman/DHC etc.. and receive a 200 OK response.

However, when I call this same address with HttpURLConnection through my android device, I receive a 401 response.

Noob developer here - any ideas as to what might be causing this would be greatly appreciated!

Edit to include my GET Request:

@Override
protected String doInBackground(String... params){
    String stringUrl = params[0];
    String result;
    String inputLine;
    try {
        //Create a URL object holding our url
        URL myUrl = new URL(stringUrl);
        //Create a connection
        HttpURLConnection connect =(HttpURLConnection)
                myUrl.openConnection();
        connect.setRequestMethod(REQUEST_METHOD); // GET
        connect.setRequestProperty("Host", HOST);
        connect.setRequestProperty("Connection", "keep-alive");
        connect.setRequestProperty("Origin", ORIGIN);
        connect.setRequestProperty("User-Agent", System.getProperty("http.agent"));
        connect.setRequestProperty("Content-Type", CONTENT_TYPE);
        connect.setRequestProperty("Accept", "*/*");
        connect.setRequestProperty("Accept-Encoding", ACCEPT_ENCODING);
        connect.setRequestProperty("Accept-Language", ACCEPT_LANGUAGE);

        connect.setDoOutput(true);
        connect.setDoInput(true);

        //Connect to our url
        connect.connect();
        String responseMessage = connect.getResponseMessage();  // Unathorized
        int responseCode = connect.getResponseCode();   //401
        //Create a new InputStreamReader
        InputStreamReader streamReader = new
                InputStreamReader(connect.getInputStream());
        //Create a new buffered reader and String Builder
        BufferedReader reader = new BufferedReader(streamReader);
        StringBuilder stringBuilder = new StringBuilder();
        //Check if the line we are reading is not null
        while((inputLine = reader.readLine()) != null){
            stringBuilder.append(inputLine);
        }
        //Close our InputStream and Buffered reader
        reader.close();
        streamReader.close();
        //Set our result equal to our stringBuilder
        result = stringBuilder.toString();
    }
    catch(IOException e){
        e.printStackTrace();
        result = null;
    }
    return result;
}

Answer 1

Replace:-

InputStreamReader streamReader = new InputStreamReader(connect.getInputStream());

With:-

InputStreamReader streamReader = new InputStreamReader(connect.getErrorStram());

This will help you track why 401 then you can proceed solving that issue.

401-- is server side problem, Server is unable to process you request, check if you have to pass data in header or url as you are using get request