Сокеты C# (TCP и UDP)

Вы можете использовать как TCP, так и UDP на одном и том же порту. Смотрите также:

Могут ли сокеты TCP и UDP использовать один и тот же порт?

Пример ниже демонстрирует, что вы можете одновременно отправлять и получать сообщения UDP и TCP.

Возможно, проблема заключается в создании вашего UdpClient для прослушивания входящих дейтаграмм. Я рекомендую создать его один раз, как ваш TcpListener.

Серверы:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace TCPUDPServer
{
  class Program
  {
    static void Main(string[] args)
    {
      TcpListener tcpServer = null;
      UdpClient   udpServer = null;
      int         port      = 59567;

      Console.WriteLine(string.Format("Starting TCP and UDP servers on port {0}...", port));

      try
      {
        udpServer = new UdpClient(port);
        tcpServer = new TcpListener(IPAddress.Any, port);

        var udpThread          = new Thread(new ParameterizedThreadStart(UDPServerProc));
        udpThread.IsBackground = true;
        udpThread.Name         = "UDP server thread";
        udpThread.Start(udpServer);

        var tcpThread          = new Thread(new ParameterizedThreadStart(TCPServerProc));
        tcpThread.IsBackground = true;
        tcpThread.Name         = "TCP server thread";
        tcpThread.Start(tcpServer);

        Console.WriteLine("Press <ENTER> to stop the servers.");
        Console.ReadLine();
      }
      catch (Exception ex)
      {
        Console.WriteLine("Main exception: " + ex);
      }
      finally
      {
        if (udpServer != null)
          udpServer.Close();

        if (tcpServer != null)
          tcpServer.Stop();
      }

      Console.WriteLine("Press <ENTER> to exit.");
      Console.ReadLine();
    }

    private static void UDPServerProc(object arg)
    {
      Console.WriteLine("UDP server thread started");

      try
      {
        UdpClient server = (UdpClient)arg;
        IPEndPoint remoteEP;
        byte[] buffer;

        for(;;)
        {
          remoteEP = null;
          buffer   = server.Receive(ref remoteEP);

          if (buffer != null && buffer.Length > 0)
          {
            Console.WriteLine("UDP: " + Encoding.ASCII.GetString(buffer));
          }
        }
      }
      catch (SocketException ex)
      {
        if(ex.ErrorCode != 10004) // unexpected
          Console.WriteLine("UDPServerProc exception: " + ex);
      }
      catch (Exception ex)
      {
        Console.WriteLine("UDPServerProc exception: " + ex);
      }

      Console.WriteLine("UDP server thread finished");
    }

    private static void TCPServerProc(object arg)
    {
      Console.WriteLine("TCP server thread started");

      try
      {
        TcpListener server = (TcpListener)arg;
        byte[]      buffer = new byte[2048];
        int         count; 

        server.Start();

        for(;;)
        {
          TcpClient client = server.AcceptTcpClient();

          using (var stream = client.GetStream())
          {
            while ((count = stream.Read(buffer, 0, buffer.Length)) != 0)
            {
              Console.WriteLine("TCP: " + Encoding.ASCII.GetString(buffer, 0, count));
            }
          }
          client.Close();
        }
      }
      catch (SocketException ex)
      {
        if (ex.ErrorCode != 10004) // unexpected
          Console.WriteLine("TCPServerProc exception: " + ex);
      }
      catch (Exception ex)
      {
        Console.WriteLine("TCPServerProc exception: " + ex);
      }

      Console.WriteLine("TCP server thread finished");
    }
  }
}

Клиенты:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading.Tasks;

namespace TCPUDPClient
{
  class Program
  {
    static void Main(string[] args)
    {
      UdpClient      udpClient = null;
      TcpClient      tcpClient = null;
      NetworkStream  tcpStream = null;
      int            port      = 59567;
      ConsoleKeyInfo key;
      bool           run = true;
      byte[]         buffer;

      Console.WriteLine(string.Format("Starting TCP and UDP clients on port {0}...", port));

      try
      {
        udpClient = new UdpClient();
        udpClient.Connect(IPAddress.Loopback, port);

        tcpClient = new TcpClient();
        tcpClient.Connect(IPAddress.Loopback, port);

        while(run)
        {
          Console.WriteLine("Press 'T' for TCP sending, 'U' for UDP sending or 'X' to exit.");
          key = Console.ReadKey(true);

          switch (key.Key)
          {
            case ConsoleKey.X:
              run = false;
              break;

            case ConsoleKey.U:
              buffer = Encoding.ASCII.GetBytes(DateTime.Now.ToString("HH:mm:ss.fff"));
              udpClient.Send(buffer, buffer.Length);
              break;

            case ConsoleKey.T:
              buffer = Encoding.ASCII.GetBytes(DateTime.Now.ToString("HH:mm:ss.fff"));

              if (tcpStream == null)
                tcpStream = tcpClient.GetStream();

              tcpStream.Write(buffer, 0, buffer.Length);
            break;
          }
        }
      }
      catch (Exception ex)
      {
        Console.WriteLine("Main exception: " + ex);
      }
      finally
      { 
        if(udpClient != null)
          udpClient.Close();

        if(tcpStream != null)
          tcpStream.Close();

        if(tcpClient != null)
          tcpClient.Close();
      }

      Console.WriteLine("Press <ENTER> to exit.");
      Console.ReadLine();
    }
  }
}