C# UDP listener not accepting packets untill another program sends something

Right, hopefully a quick question & answer. My application is supposed to listen on an UDP port and from any IP Address from a certain showcontrol server. Which just sends out plain ASCII text/strings.

Since we do not have such a S.C. server at the office I also wrote a very small simple console application that just broadcasts UDP packets.

This is the console app:

    static void Main(string[] args)
    {

        Thread.Sleep(1000);

        Socket soc = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
        IPEndPoint e = new IPEndPoint(IPAddress.Broadcast, 35000);

        IPAddress broadcast = IPAddress.Parse("192.168.1.255");

        e = new IPEndPoint(broadcast, 35000);

        string s;
        Byte[] sendBytes;

        while ("exit" != (s = Console.ReadLine()))
        {
            sendBytes = Encoding.ASCII.GetBytes((s.EndsWith("\n") ? s : s + "\n"));
            soc.SendTo(sendBytes, e);
        }

        sendBytes = Encoding.ASCII.GetBytes("EXIT\n");
        soc.SendTo(sendBytes, e);

        soc.Close();
    }

I've tried two things on the listener part. Using UdpClient and using a socket connection and both are giving me the exact same problem which I will describe below both my listener code:

The Socket version:

    public MediaPlayer(Output outputWindow)
    {
        Socket serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

        IPEndPoint ipEndPoint = new IPEndPoint(IPAddress.Any, i_inPort);

        serverSocket.Bind(ipEndPoint);

        IPEndPoint ipeSender = new IPEndPoint(IPAddress.Any, 0);

        EndPoint epSender = (EndPoint)ipeSender;

        SocketState state = new SocketState();
        state.e = epSender;
        state.s = serverSocket;

        beginReceiveFrom(state);
    }
    public void beginReceiveFrom(SocketState state)
    {
        state.byteData = new byte[state.byteData.Length];
        IPEndPoint ipeSender = new IPEndPoint(IPAddress.Any, 0);
        state.e = (EndPoint)ipeSender;

        state.s.BeginReceiveFrom(state.byteData, 0, state.byteData.Length, SocketFlags.None, ref state.e, onReceiveFrom, state);
    }

    public void onReceiveFrom(IAsyncResult ar)
    {
        SocketState state = (SocketState)ar.AsyncState;
        Socket serverSocket = state.s;
        //EndPoint epSender = state.e;

        IPEndPoint ipeSender = new IPEndPoint(IPAddress.Any, 0);
        EndPoint epSender = (EndPoint)ipeSender;
        try
        {
            serverSocket.EndReceiveFrom(ar, ref epSender);

            string s = Encoding.ASCII.GetString(state.byteData);
        }
        catch (System.Exception ex)
        {
            Console.WriteLine(ex);
        }
        finally
        {
            beginReceiveFrom(state);
        }
    }

The UdpClient version:

    public MediaPlayer(Output outputWindow)
    {
        UdpClient client = new UdpClient(i_inPort);
        IPEndPoint endPoint = null;

        UdpState state = new UdpState();

        state.e = endPoint;
        state.u = client;
    }

    private void BeginReceive(UdpState state)
    {
        state.u.BeginReceive(new AsyncCallback(ReceiveCallback), state);
    }

    private void ReceiveCallback(IAsyncResult ar)
    {
        UdpState state = null;

        try
        {
            state = (UdpState)ar.AsyncState;

            Byte[] receiveBytes = state.u.EndReceive(ar, ref state.e);
            string receiveString = Encoding.ASCII.GetString(receiveBytes);

            executive.Receive(receiveString);

            BeginReceive(state);
        }
        catch(System.Exception ex)
        {
            SetText(ex.ToString());
        }       
    }

There is some extra code in the UpdClient ReceiveCallback version because that is the one I initially used. The problem is, is that when I am sending/broadcasting stuff with the console app within anyway in my companies network and on any computer it just works, no problem. Multiple medi开发者_StackOverflow社区aplayers can be playing on any amount of computers with no problem.

However, when I am using a different UDP sender (Something like Hercules from hw-group.com) then it simply wont work, >untill< I send one command with my console app. Only then, after sending a text/packet/data with my console app will my applcation accept data from the hercules application.

Is there anyone seeing what I am doing wrong? I've read multiple code examples, from here, codeproject and guru-something, and they are all using the same type of programming that I used.

Also, sorry for the wall of text.

---

probable the header of the packets it's not present in the message you're sending to the devices, double check that and make sure you message is being decoded correctly.