TCP сокет на Android Studio

Есть серверная часть написанная на C# и есть клиентская часть, написанная на Java под андроид. При попытке подключения телефона к серверу вылетает все время одна ошибка. Час блуждания по гуглу не дал результатов.

(C#) Сервер:

        string path = @"C:\Users\sdfaf\Downloads\Ubuntu-logo-large.png";
        byte[] img = File.ReadAllBytes(path);
        TcpListener listener = new TcpListener(IPAddress.Any, 2700);
        listener.Start();
        Console.WriteLine("Жду...");
        TcpClient client = listener.AcceptTcpClient();
        Console.WriteLine("Дождался");
        byte[] buff = new byte[1024];
        int size = client.GetStream().Read(buff, 0, buff.Length);
        string msg = Encoding.ASCII.GetString(buff, 0, size);
        Console.WriteLine(msg);
        if (msg == "image")
        {
            client.GetStream().Write(img, 0, img.Length);
            Console.WriteLine("Отправил");
        }
        client.Close();
        listener.Stop();

Клиент:

package test.testapp;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.Socket;
public class MainActivity extends Activity
{
    private ImageView img;
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_layout);
        img = findViewById(R.id.imageView);
    }
    public void downloadImage(View view) {
        byte buff[];
        Socket socket = null;
        try {
            socket = new Socket("192.168.1.2", 2700);
        } catch (IOException e) {
            e.printStackTrace();
        }
        PrintWriter pw = null;
        try {
            pw = new PrintWriter(socket.getOutputStream());
        } catch (IOException e) {
            e.printStackTrace();
        }
        pw.write("image");
        pw.flush();
        buff = new byte[128 * 1024];
        int size = 0;
        try {
            size = socket.getInputStream().read(buff);
        } catch (IOException e) {
            e.printStackTrace();
        }
        Bitmap bmp = BitmapFactory.decodeByteArray(buff, 0, size);
        img.setImageBitmap(bmp);
        try {
            socket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Манифест:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="test.testapp">
    <uses-permission android:name="android.permission.INTERNET" />
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Ошибка:

> E/AndroidRuntime: FATAL EXCEPTION: main
    Process: test.testapp, PID: 21978
    java.lang.IllegalStateException: Could not execute method for android:onClick
        at android.view.View$DeclaredOnClickListener.onClick(View.java:4543)
        at android.view.View.performClick(View.java:5317)
        at android.view.View$PerformClick.run(View.java:21648)
        at android.os.Handler.handleCallback(Handler.java:815)
        at android.os.Handler.dispatchMessage(Handler.java:104)
        at android.os.Looper.loop(Looper.java:207)
        at android.app.ActivityThread.main(ActivityThread.java:5933)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:958)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:819)
     Caused by: java.lang.reflect.InvocationTargetException
        at java.lang.reflect.Method.invoke(Native Method)
        at android.view.View$DeclaredOnClickListener.onClick(View.java:4538)
        at android.view.View.performClick(View.java:5317) 
        at android.view.View$PerformClick.run(View.java:21648) 
        at android.os.Handler.handleCallback(Handler.java:815) 
        at android.os.Handler.dispatchMessage(Handler.java:104) 
        at android.os.Looper.loop(Looper.java:207) 
        at android.app.ActivityThread.main(ActivityThread.java:5933) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:958) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:819) 
     Caused by: android.os.NetworkOnMainThreadException
        at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1321)
        at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:110)
        at libcore.io.IoBridge.connectErrno(IoBridge.java:150)
        at libcore.io.IoBridge.connect(IoBridge.java:133)
        at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:188)
        at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:168)
        at java.net.Socket.startupSocket(Socket.java:627)
        at java.net.Socket.tryAllAddresses(Socket.java:137)
        at java.net.Socket.<init>(Socket.java:187)
        at java.net.Socket.<init>(Socket.java:159)
        at test.testapp.MainActivity.downloadImage(MainActivity.java:32)
        at java.lang.reflect.Method.invoke(Native Method) 
        at android.view.View$DeclaredOnClickListener.onClick(View.java:4538) 
        at android.view.View.performClick(View.java:5317) 
        at android.view.View$PerformClick.run(View.java:21648) 
        at android.os.Handler.handleCallback(Handler.java:815) 
        at android.os.Handler.dispatchMessage(Handler.java:104) 
        at android.os.Looper.loop(Looper.java:207) 
        at android.app.ActivityThread.main(ActivityThread.java:5933) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:958) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:819)