Can't read/write data (TcpClient/NetworkStream) - unity3d

Question

A former employees used TCP Client & TCP Listener, Thread, and NetworkStream to create a payment server with Unity 32-bit for Unity 32-bit games and payment connections.
(I don't know what I'm talking about either)
BUT Only the first payment is successful, and the second payment cannot be 'Read' even if it is 'Write'.
(Or maybe client server listener(?) is dumb.... ;( )
So I tried debugging, but this comment came up.
'SocketException System.Net.Sockets.SocketException: Blocking operation aborted by calling WSACanceBlockingCall.'
I can't even connect to the clientServer.
It's fatal to the company that only one payment is made.
This is because after the payment, the game proceeds and when the GameLife is exhausted, you have to return to the lobby and pay again.
But "Write" works, but why doesn't it go on after that?
If you are disconnected from the game and payment server, you will be warned that you are disconnected from the server.
I'm so confused. I'm a client developer and I don't understand anything because I think I'm developing a server.
I'm just a three-month-old junior developer...
This is my client Write Code
public void SendMessage()
{
if (socketConnection == null)
{
return;
}
try
{
// Get a stream object for writing.
NetworkStream stream = socketConnection.GetStream();
if (stream.CanWrite)
{
//string clientMessage = "This is a message from one of your clients.";
string clientMessage = string.Format("Charge,{0}",DataManager.instance.payData._Money);
// Convert string message to byte array.
//byte[] clientMessageAsByteArray = Encoding.ASCII.GetBytes(clientMessage);
byte[] clientMessageAsByteArray = Encoding.UTF8.GetBytes(clientMessage);
// Write byte array to socketConnection stream.
stream.Write(clientMessageAsByteArray, 0, clientMessageAsByteArray.Length);
Debug.Log("Client sent his message - should be received by server");
}
}
catch (SocketException socketException)
{
serverState = ServerState.Disconnect;
Debug.Log("Socket exception: " + socketException);
}
}
This is Server Read Code
private void ListenForIncomingRequests()
{
try
{
// Get Local IPv4 Address
IPHostEntry host = Dns.GetHostEntry(Dns.GetHostName());
foreach (var ip in host.AddressList)
{
if (ip.AddressFamily == AddressFamily.InterNetwork)
{
address = ip.ToString();
}
}
Debug.Log("address : "+ address);
// Create listener on localhost port 8052.
tcpListener = new TcpListener(IPAddress.Parse(address), 50001);
tcpListener.Start();
Debug.Log("Server is listening");
Byte[] bytes = new Byte[1024];
while (true)
{
using (connectedTcpClient = tcpListener.AcceptTcpClient())
{
Debug.Log(connectedTcpClient.ToString());
// Get a stream object for reading
using (NetworkStream stream = connectedTcpClient.GetStream())
{
int length;
// Read incoming stream into byte arrary.
while ((length = stream.Read(bytes, 0, bytes.Length)) != 0)
{
var incomingData = new byte[length];
Array.Copy(bytes, 0, incomingData, 0, length);
// Convert byte array to string message.
//string clientMessage = Encoding.ASCII.GetString(incomingData);
string[] message = Encoding.UTF8.GetString(incomingData).Split(',');
string clientMessage = message[0];
string value = message[1];
if (string.IsNullOrEmpty(_clientMessage))
{
_clientMessage = clientMessage;
if (_clientMessage.Equals("Charge"))
{
_clientMessage = string.Empty;
pay.PayEvent(int.Parse(value));
}
}
Debug.Log("client message received as: " + clientMessage);
Debug.Log("_client message received as: " + _clientMessage);
Debug.Log(length);
}
}
}
}
}
catch (SocketException socketException)
{
Debug.Log("SocketException " + socketException.ToString());
}
}