C# tcplistener , port stop listen at random time

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C#

.NET

I am new to C# and .net core. I am building a billing program where PBX send data as client on defined TCP port .
I created project in C# and it is working fine, means I can listen on port and get data from client.
But for some random reason port stop listening and I can confirm this from window server resource monitor Network --> Listening Ports.
I can also confirm there is port overlapping means no other software use that port.
But if I restart service it start to listen on port again.
I want port to never stop listen on that TCP port, and if for any reason it stop , it should automatically start to listen again.
Client software and billing program are installed on same PC.

What I have tried:

<pre lang="C#"><pre>
using CDR.Models;
using Newtonsoft.Json;
using RestSharp;
using System;
using System.IO;
using System.Net;
using System.Net.Sockets;

namespace CDR.Helpers
{
    /// <summary>
    /// Active or Passive.
    /// </summary>
    public class CDRServer
    {
        public static void Listen()
        {
            Logger.Log("Starting 3cX Listener");

            TcpListener server = null;
            try
            {
                // Set the TcpListener on port 13000.
                Int32 port = 5015;

                // IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());
                // if (!ipHostInfo.AddressList.Any(d => d.AddressFamily == AddressFamily.InterNetwork))
                //   return;
                //IPAddress ipAddress = ipHostInfo.AddressList.FirstOrDefault(d => d.AddressFamily == AddressFamily.InterNetwork);//IPAddress.Parse("127.0.0.1");//

                IPAddress ipAddress = IPAddress.Parse("127.0.0.1");

                // TcpListener server = new TcpListener(port);
                server = new TcpListener(ipAddress, port);

                // Start listening for client requests.
                server.Start();

                // Buffer for reading data
                Byte[] bytes = new Byte[1024]; //this can be received.  //INVESTIGATE

                //100KB

                String data = null;

                // Enter the listening loop.
                while (true)
                {
                    Console.WriteLine($"Waiting for a connection...  on {ipAddress.ToString()} and {port.ToString()}");
                    Logger.Log($"Waiting for a connection...  on {ipAddress.ToString()} and {port.ToString()}");
                    // Perform a blocking call to accept requests.
                    // You could also user server.AcceptSocket() here.
                    TcpClient client = server.AcceptTcpClient();
                    Console.WriteLine("Connected!");
                    Logger.Log("Connected!");

                    data = null;

                    // Get a stream object for reading and writing
                    NetworkStream stream = client.GetStream();

                    int i;

                    // Loop to receive all the data sent by the client.
                    while ((i = stream.Read(bytes, 0, bytes.Length)) != 0)
                    {
                        // Translate data bytes to a ASCII string.
                        data = System.Text.Encoding.ASCII.GetString(bytes, 0, i);

                        Console.WriteLine("Received: {0}", data);

                        //process the received call data and then save it to the database. 
                        Logger.Log($"Received: {data}");

                        try
                        {
                            CDRModel cdr = new CDRModel();
                            var datasplit = data.Split(',');

                            cdr.historyidofthecall = datasplit[0];
                            cdr.callid = datasplit[1];
                            cdr.duration = datasplit[2];

                            Logger.Log($"Before Date: {DateTime.Parse(datasplit[3]).ToString()}");
                            cdr.timestart = DateTime.Parse(datasplit[3]);//.Zone().AddHours(-3);
                            Logger.Log($"After Date: {cdr.timestart.ToString()}");

                            if (!string.IsNullOrEmpty(datasplit[4]))
                            {
                                cdr.timeanswered = DateTime.Parse(datasplit[4]);//.Zone().AddHours(-3);
                            }
                            cdr.timeend = DateTime.Parse(datasplit[5]);//.Zone().AddHours(-3);

                            cdr.reason_termination = datasplit[6];
                            cdr.from_no = datasplit[7];
                            cdr.to_no = datasplit[8];
                            cdr.from_dn = datasplit[9];
                            cdr.to_dn = datasplit[10];
                            cdr.dial_no = datasplit[11];
                            cdr.reason_changed = datasplit[12];
                            cdr.final_number = datasplit[13];
                            cdr.final_dn = datasplit[14];
                            cdr.from_type = datasplit[15];
                            cdr.missed_queue_calls = datasplit[16];
                            cdr.chain = datasplit[17];
                            //cDR.Chain = dataSplit[19];

                            // Process the data sent by the client add to the database.
                            //using (var context = new MySqlContext())
                            //{
                            //    context.CDRs.Add(cDR);
                            //    context.SaveChanges();
                            //}

                            //Post object to external server. 
                            Logger.Log(JsonConvert.SerializeObject(cdr));

                            //var url = Environment.GetEnvironmentVariable("cdrlink");
                            if (!File.Exists("Db.txt"))
                                Console.WriteLine("Db.txt file not found");
                            var url = File.ReadAllText(@"Db.txt");
                            Logger.Log(url);
                            RestClient client2 = new RestClient(url);
                            
                            RestRequest request = new RestRequest(Method.POST);
                            request.AddParameter("application/json", JsonConvert.SerializeObject(cdr), ParameterType.RequestBody);
                            var response = client2.Execute(request);
                        }
                        catch (Exception ex)
                        {
                            Logger.Log(ex);
                        }


                        //byte[] msg = System.Text.Encoding.ASCII.GetBytes(data);

                        // Send back a response.
                        //stream.Write(msg, 0, msg.Length);
                        //Console.WriteLine("Sent: {0}", data);
                    }

                    // Shutdown and end connection
                    client.Close();
                    Logger.Log("Client Closed");

                }
            }
            catch (SocketException e)
            {
                Console.WriteLine("SocketException: {0}", e);
                Logger.Log(e);
            }
            finally
            {
                // Stop listening for new clients.
                server.Stop();
                Logger.Log("Server Stopped");
            }


            Console.WriteLine("\nHit enter to continue...");
            Console.Read();

        }

    }

}