Sending an UDP message over WiFi causes UnkownHostException and SocketException

Question

I want to send an UDP packet form my mobile device to my computer, but when I try to initiate a DatagramSocket or use the InetAddress.getByName() method the compiler shows the folowing errors:

DatagramSocket: "Unhandeld Exception: java.net.UnknowHostException"

InetAddress: "Unhandeld Exception: java.net.SocketException"

I also added a few user-permission tags in the AndroidMafinest.xml file, but without result.

PacketService.java

package mw.mobilepccommunication;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

public class PacketService {

    private String mIP;
    private int mPort;

    public PacketService (String aIP, int aPort)
    {
        mIP = aIP;
        mPort = aPort;
    }

    public void lockHandler ()
    {
        String lMessage = "TEST";
        InetAddress lLocal = InetAddress.getByName(mIP); //<--UnknownHostException
        int lMessageLength = lMessage.length();
        byte [] lBuffer = lMessage.getBytes();

        DatagramSocket lSocket = new DatagramSocket(mPort); // <--SocketException 

        DatagramPacket lPacket = new DatagramPacket(lBuffer, lMessageLength, lLocal, mPort);
    }

}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="mw.mobilepccommunication" >

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.READ_PHONE_STATE" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>