Stream audio on some mobile models does not work

I am completing a simple audio stream (Web Radio) for finalizing a project in my city. I am still new to the programming area of app , however I noticed that some Smartphone models (Moto Xplay and Sony Xpéria) , the stream does not run, however doing tests on my model ( A5) the stream plays normally.

I have already declared all possible permissions that could be made, but I am not finding a solution in this case.

package conciso.radioweb156natal;

import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;


import java.io.IOException;

public class MainActivity extends AppCompatActivity {

    Button b_play;
    MediaPlayer mediaPlayer;

    boolean prepared = false;
    boolean started = false;
    boolean primeiraExecucao = true;

    String url = "http://radio.imd.ufrn.br/156natal";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        b_play = (Button) findViewById(R.id.b_play);
        b_play.setEnabled(false);
        b_play.setText("   CONECTANDO...    ");

        mediaPlayer = new MediaPlayer();
        mediaPlayer.setAudioSessionId(AudioManager.STREAM_MUSIC);

        new PlayerTask().execute(url);


        b_play.setOnClickListener (new View.OnClickListener(){
            @Override
            public void onClick (View view) {
                if(started){
                    started = false;
                    mediaPlayer.start();
                    b_play.setText("PAUSE");
                } else {
                    started = true;
                    mediaPlayer.pause();
                    b_play.setText("PLAY");
                }
            }

        });
    }
    class PlayerTask extends AsyncTask<String, Void, Boolean> {
        @Override
        protected Boolean doInBackground(String... strings) {

            try {
                mediaPlayer.setDataSource(strings[0]);
                mediaPlayer.prepare();
                prepared = true;
                mediaPlayer.start();
            } catch (IOException e) {
                e.printStackTrace();
            }

            return prepared;
        }

        @Override
        protected void onPostExecute(Boolean aBoolean) {
            super.onPostExecute(aBoolean);
            if(primeiraExecucao){
                b_play.setEnabled(true);
                b_play.setText("Pause");
                primeiraExecucao = false;
            }
            else {
                b_play.setEnabled(true);
                b_play.setText("PLAY");
            }
        }
    }

    @Override
    protected void onPause() {
        super.onPause();
        if(started){
            mediaPlayer.pause();
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        if(started){
            mediaPlayer.start();
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if(prepared){
            mediaPlayer.release();
        }
    }

    public void clickexit(View v) {
        started = false;
        b_play.setText("PAUSE");
        this.finish();
    }

    @Override
    public void onBackPressed() {
        moveTaskToBack(true);
    }
}