I am trying to connect the server using ASP.Net Core 6. When I run it on my localhost it works fine, but when I publish on the server I get an error.I published my Server project to FileZilla. IP address, and port are correct. However, i got this error message:

Socket connected.
Sent 19 bytes to server.
System.Net.Sockets.SocketException (10054): An existing connection was forcibly closed by a remote host. at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.ThrowException(SocketError error, CancellationToken cancellationToken) at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token) at System.Threading.Tasks.ValueTask`1.ValueTaskSourceAsTask.<>c.<.cctor>b__4_0(Object state) --- End of stack trace from previous location --- at System.Threading.Tasks.TaskToApm.End[TResult](IAsyncResult asyncResult) at System.Net.Sockets.Socket.EndReceive(IAsyncResult asyncResult) at AsynchronousClient.ReceiveCallback(IAsyncResult ar) in C:\Users\rozer\source\repos\Client1\Client1\Program.cs:line 129

The error line:

int bytesRead = client.EndReceive(ar);

I understood that the connection has been made. But ı do not understand why it is forcibly closed by a remote host and I got this error. Is it about a firewall issue or something like that? And how can i solve this problem?

This is my Client project to check the connection:

using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Text;

// State object for receiving data from remote device.  
public class StateObject
{
    // Client socket.  
    public Socket workSocket = null;
    // Size of receive buffer.  
    public const int BufferSize = 256;
    // Receive buffer.  
    public byte[] buffer = new byte[BufferSize];
    // Received data string.  
    public StringBuilder sb = new StringBuilder();
}

public class AsynchronousClient
{
    // The port number for the remote device.  
    private const int port = 443;

    // ManualResetEvent instances signal completion.  
    private static ManualResetEvent connectDone =
        new ManualResetEvent(false);
    private static ManualResetEvent sendDone =
        new ManualResetEvent(false);
    private static ManualResetEvent receiveDone =
        new ManualResetEvent(false);

    // The response from the remote device.  
    private static String response = String.Empty;

    private static void StartClient()
    {
        // Connect to a remote device.  
        try
        {
            // Establish the remote endpoint for the socket.  
            // The name of the
            // remote device is "host.contoso.com".  
            IPHostEntry ipHostInfo = Dns.GetHostEntry("networks.net");
            IPAddress ipAddress = ipHostInfo.AddressList[0];
            IPEndPoint remoteEP = new IPEndPoint(ipAddress, port);

            // Create a TCP/IP socket.  
            Socket client = new Socket(ipAddress.AddressFamily,
                SocketType.Stream, ProtocolType.Tcp);

            // Connect to the remote endpoint.  
            client.BeginConnect(remoteEP,
                new AsyncCallback(ConnectCallback), client);
            connectDone.WaitOne();

            // Send test data to the remote device.  
            Send(client, "deneme fkfglb ");
            sendDone.WaitOne();

            // Receive the response from the remote device.  
            Receive(client);
            receiveDone.WaitOne();

            // Write the response to the console.  
            Console.WriteLine("Response received : {0}", response);

            // Release the socket.  
            client.Shutdown(SocketShutdown.Both);
            client.Close();

        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }
    }

    private static void ConnectCallback(IAsyncResult ar)
    {
        try
        {
            // Retrieve the socket from the state object.  
            Socket client = (Socket)ar.AsyncState;

            // Complete the connection.  
            client.EndConnect(ar);

            Console.WriteLine("Socket connected to {0}",
                client.RemoteEndPoint.ToString());

            // Signal that the connection has been made.  
            connectDone.Set();
        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }
    }

    private static void Receive(Socket client)
    {
        try
        {
            // Create the state object.  
            StateObject state = new StateObject();
            state.workSocket = client;

            // Begin receiving the data from the remote device.  
            client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                new AsyncCallback(ReceiveCallback), state);
        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }
    }

    private static void ReceiveCallback(IAsyncResult ar)
    {
        try
        {
            // Retrieve the state object and the client socket
            // from the asynchronous state object.  
            StateObject state = (StateObject)ar.AsyncState;
            Socket client = state.workSocket;

            // Read data from the remote device.  
            int bytesRead = client.EndReceive(ar);

            if (bytesRead > 0)
            {
                // There might be more data, so store the data received so far.  
                state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead));

                // Get the rest of the data.  
                client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                    new AsyncCallback(ReceiveCallback), state);
            }
            else
            {
                // All the data has arrived; put it in response.  
                if (state.sb.Length > 1)
                {
                    response = state.sb.ToString();
                }
                // Signal that all bytes have been received.  
                receiveDone.Set();
            }
        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }
    }

    private static void Send(Socket client, String data)
    {
        // Convert the string data to byte data using ASCII encoding.  
        byte[] byteData = Encoding.ASCII.GetBytes(data);

        // Begin sending the data to the remote device.  
        client.BeginSend(byteData, 0, byteData.Length, 0,
            new AsyncCallback(SendCallback), client);
    }

    private static void SendCallback(IAsyncResult ar)
    {
        try
        {
            // Retrieve the socket from the state object.  
            Socket client = (Socket)ar.AsyncState;

            // Complete sending the data to the remote device.  
            int bytesSent = client.EndSend(ar);
            Console.WriteLine("Sent {0} bytes to server.", bytesSent);

            // Signal that all bytes have been sent.  
            sendDone.Set();
        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }
    }

    public static int Main(String[] args)
    {
        StartClient();
        return 0;
    }
} ```