Add project files.

MultiThreadTCP.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.5.33103.201
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "MultiThreadTCPServer", "MultiThreadTCPServer\MultiThreadTCPServer.csproj", "{7C366206-F583-4E04-9715-AA36E8FFB3A8}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{7C366206-F583-4E04-9715-AA36E8FFB3A8}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{7C366206-F583-4E04-9715-AA36E8FFB3A8}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{7C366206-F583-4E04-9715-AA36E8FFB3A8}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{7C366206-F583-4E04-9715-AA36E8FFB3A8}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {AB0227F1-F1EC-4BAB-B88B-D7B7DAB5E24E}
+	EndGlobalSection
+EndGlobal

MultiThreadTCPServer/MultiThreadTCPServer.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

MultiThreadTCPServer/Program.cs

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+// See https://aka.ms/new-console-template for more information
+Console.WriteLine("Hello, World!");

MultiThreadTCPServer/Server.cs

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+using System.Net;
+using System.Net.Sockets;
+using System.Text;
+
+namespace MultiThreadTCPServer
+{
+    class Server
+    {
+        TcpListener _server = null;
+
+        public Server(string ip, int port)
+        {
+            IPAddress localAddr = IPAddress.Parse(ip);
+            _server = new TcpListener(localAddr, port);
+            _server.Start();
+            StartListener();
+        }
+
+        private void StartListener()
+        {
+            try
+            {
+                while (true)
+                {
+                    Console.WriteLine("Waiting for a connection...");
+                    TcpClient client = _server.AcceptTcpClient();
+                    Console.WriteLine("Connected!");
+
+                    Thread t = new Thread(new ParameterizedThreadStart(HandleClient));
+                    t.Start();
+                }
+            }
+            catch (SocketException e)
+            {
+                Console.WriteLine("SocketException: {0}", e);
+                _server.Stop();
+            }
+        }
+
+        private void HandleClient(object? obj)
+        {
+            TcpClient client = (TcpClient)obj;
+            var stream = client.GetStream();
+
+            string imei = String.Empty;
+
+            string data = String.Empty;
+
+            Byte[] bytes = new Byte[256];
+            int i;
+
+            try
+            {
+                while ((i = stream.Read(bytes, 0, bytes.Length)) != 0)
+                {
+                    string hex = BitConverter.ToString(bytes);
+                    data = Encoding.ASCII.GetString(bytes, 0, i);
+                    Console.WriteLine($"{data}: Received: {Thread.CurrentThread.ManagedThreadId}");
+
+                    string str = "Hey Client!";
+                    Byte[] reply = System.Text.Encoding.ASCII.GetBytes(str);
+                    stream.Write(reply, 0, reply.Length);
+                    Console.WriteLine($"{Thread.CurrentThread.ManagedThreadId}: Sent: {str}");
+                }
+                     
+            }
+            catch (Exception e)
+            {
+                Console.WriteLine("Exception: {0}", e.ToString());
+                client.Close();
+            }
+        }
+    }
+}