NetworkStream.DataAvailable is true even if there is no data on server side

Question

I have 2 simple applications - server and client. For now, server just waiting for a client to connect, prints networkstream.DataAvailable status, freezes for 5 sec and prints networkstream.DataAvailable status again. Client does the same thing, except it doesn't wait for connection but connects to server. Server-side code:

 static void Main(string[] args)
    {           
        int port = 8880;
        IPAddress localAddress = IPAddress.Parse("127.0.0.1");

        TcpListener serverListener = new TcpListener(localAddress, port);
        serverListener.Start();
        TcpClient incomingConnection = serverListener.AcceptTcpClient();
        IPEndPoint RemAddr = (IPEndPoint)incomingConnection.Client.RemoteEndPoint; ;
        Console.WriteLine("Connection: {0}:{1}", RemAddr.Address, RemAddr.Port);

        NetworkStream networkStream = incomingConnection.GetStream();

        StreamWriter sw = new StreamWriter(networkStream, Encoding.UTF8) { AutoFlush = true };            
        Console.WriteLine("networkstream.DataAvailable is {0}", networkStream.DataAvailable);
        Thread.Sleep(5000);
        Console.WriteLine("networkstream.DataAvailable is {0}", networkStream.DataAvailable);
        ...

Client-side code:

static void Main(string[] args)
    {
        IPAddress remoteaddr = IPAddress.Parse("127.0.0.1");

        int port = 8880;
        TcpClient tcpclient = new TcpClient();
        tcpclient.Connect(remoteaddr, port);
        NetworkStream networkstream = tcpclient.GetStream();
        StreamWriter sw = new StreamWriter(networkstream, Encoding.UTF8);
        StreamReader sr = new StreamReader(networkstream, Encoding.UTF8);

        Console.WriteLine("networkstream.DataAvailable is {0}", networkstream.DataAvailable);
        Thread.Sleep(5000);
        Console.WriteLine("networkstream.DataAvailable is {0}", networkstream.DataAvailable);
        ...

So, here I have a problem. On server side I have the following output:

Connection: 127.0.0.1:55919
networkstream.DataAvailable is False
networkstream.DataAvailable is False

On server side output is:

networkstream.DataAvailable is False
networkstream.DataAvailable is True

So client shows that there is data in my networkStream. But there is no any data! And this is a problem, because in my application I use networkstream.DataAvailable to detect if there any data sent from server. So, question is - what am I doing wrong? How to check availability of data properly?

Answer 1

Thomas Levesque answered my question in comments section:

From the server perspective, there is nothing to read, since the client didn't write anything. I think the StreamWriter writes the BOM when you create it, hence the 3 bytes. And sr.Read() tries to read a character, but there is nothing to read beyond the BOM, so it blocks. – Thomas Levesque 10 mins ago