Client.cs

        static void Main(string[] args)
        {
            UdpClient udpClient = new UdpClient();
            udpClient.Connect(new IPEndPoint(IPAddress.Broadcast, 11000));
            Byte[] sendBytes = Encoding.ASCII.GetBytes("Is anybody there?");
            udpClient.Send(sendBytes, sendBytes.Length);
        }

Server.cs

        static void Main(string[] args)
        {
            IPEndPoint remoteIpEndPoint = new IPEndPoint(IPAddress.Any, 0);
            UdpClient udpClient = new UdpClient(11000);
            Byte[] receiveBytes = udpClient.Receive(ref remoteIpEndPoint);
            NetworkStream stream = new NetworkStream(udpClient.Client); // <- 'System.IO.IOException' The operation is not allowed on non-connected sockets thrown here.
        }