VPN не меняет IP-адрес с помощью PPTP в Android

Question

В основном я создаю приложение VPN, для подключения которого просто требуются имя пользователя и пароль для адреса сервера, поэтому, когда я помещаю учетные данные непосредственно в add VPN из настроек, он работает нормально, но при подключении из приложения он не работает.

Это мое основное занятие, в которое я поместил все детали напрямую.

    public class MainActivity extends AppCompatActivity {
    private static final String KEY_PASSWORD = "an4d7bm";
    private static final String KEY_USERNAME = "vpnbook";
    @SuppressLint("WrongViewCast")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button btConnect = findViewById(R.id.connect);
        btConnect.setOnClickListener(new View.OnClickListener() {
            @SuppressLint("WrongViewCast")
            @Override
            public void onClick(View v) {
                Intent intent = VpnService.prepare(getApplicationContext());
                if (intent != null) {
                    startActivityForResult(intent, 0);
                } else {
                    onActivityResult(0, RESULT_OK, null);
                }
            }
        });
    }
    @SuppressLint("MissingSuperCall")
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        Intent intent = new Intent(this, Client.class);
        EditText username = findViewById(R.id.username);
        EditText pw = findViewById(R.id.password);
        intent.putExtra(MainActivity.KEY_USERNAME, "vpnbook");
        intent.putExtra(MainActivity.KEY_PASSWORD, "an4d7bm");
        startService(intent);
    }}



    VpnService 
public class Client extends VpnService{

    private static final String TAG = "VPN";
    private Thread mThread;
    private ParcelFileDescriptor mInterface;
    //a. Configure a builder for the interface.
    Builder builder = new Builder();
    private long IDLE_INTERVAL_MS = 100;
    private long KEEPALIVE_INTERVAL_MS = 100;
    private long RECEIVE_TIMEOUT_MS = 1000;

    // Services interface
    @Override
    public int onStartCommand(final Intent intent, int flags, int startId) {

        String username = "vpnbook";
        String password = "an4d7bm";

        mThread = new Thread(() -> {

            try {

                mInterface = builder.setSession("MyVPNService")
                        .addAddress("94.23.57.8", 24)
                        .establish();

                FileInputStream in = new FileInputStream(
                        mInterface.getFileDescriptor());
                FileOutputStream out = new FileOutputStream(
                        mInterface.getFileDescriptor());
                DatagramChannel tunnel = DatagramChannel.open();

                tunnel.socket().bind(new InetSocketAddress(0));

                int port = tunnel.socket().getLocalPort();

                Log.d("VPNservice", "2 " + (tunnel != null));
                Log.d("VPNservice", "3 " + tunnel.connect(new InetSocketAddress(port)));

                tunnel.configureBlocking(false);
                protect(tunnel.socket());

                ByteBuffer packet = ByteBuffer.allocate(Short.MAX_VALUE);
                long lastReceiveTime = System.currentTimeMillis();
                long lastSendTime = System.currentTimeMillis();

                while (true) {

                    boolean idle = true;

                    int length = in.read(packet.array());

                    if (length > 0) {
                        packet.limit(length);
                        tunnel.write(packet);
                        packet.clear();
                        idle = false;
                        lastReceiveTime = System.currentTimeMillis();

                        Log.d("Log", "Write package");
                    }

                    length = tunnel.read(packet);
                    if (length > 0) {
                        if (packet.get(0) != 0){
                            out.write(packet.array(), 0, length);
                        }
                        packet.clear();
                        idle = false;
                        lastSendTime = System.currentTimeMillis();
                    }

                    if (idle) {
                        Thread.sleep(IDLE_INTERVAL_MS);
                        final long timeNow = System.currentTimeMillis();
                        if (lastSendTime + KEEPALIVE_INTERVAL_MS <= timeNow) {
                            packet.put((byte) 0).limit(1);
                            for (int i = 0; i < 3; ++i) {
                                packet.position(0);
                                tunnel.write(packet);
                            }
                            packet.clear();
                            lastSendTime = timeNow;
                        } else if (lastReceiveTime + RECEIVE_TIMEOUT_MS <= timeNow) {
                            throw new IllegalStateException("Timed out");
                        }
                    }
                }

            } catch (Exception e) {
                System.out.println(e.getMessage());
                e.printStackTrace();
            } finally {
                try {
                    if (mInterface != null) {
                        mInterface.close();
                        mInterface = null;
                    }
                } catch (Exception e) {
                    Log.d("Erro: ", e.getMessage());
                }
            }
        }, "MyVpnRunnable");

        mThread.start();
        return START_STICKY;
    }

    @Override
    public void onDestroy() {
        // TODO Auto-generated method stub
        if (mThread != null) {
            mThread.interrupt();
        }
        super.onDestroy();
    }

}