public class Class1
{
    static void Main()
    {
        string data = "Some big string...";
        Work(data);

        Console.WriteLine("Press any key for exit...");
        Console.ReadKey();
    }

    async static void Work(string data)
    {
        var guid = Guid.NewGuid();
        Uri uri = new Uri("http://localhost:61698/Home/Task/" + guid.ToString());

        using (Stream s = StringToStream(data))
        {
            var report = await PostStream(uri, guid, s);
        }
    }

    public static Stream StringToStream(string s)
    {
        MemoryStream stream = new MemoryStream();
        StreamWriter writer = new StreamWriter(stream);
        writer.Write(s);
        writer.Flush();
        stream.Position = 0;
        return stream;
    }

    async static Task<byte[]> PostStream(Uri uri, Guid guid, Stream stream)
    {
        try
        {
            using (StreamReader sr = new StreamReader(stream))
            {
                string text = await sr.ReadToEndAsync();

                var host = Dns.GetHostEntry(Dns.GetHostName());

                IPAddress ip = null;

                foreach (var item in host.AddressList)
                {
                    if (item.AddressFamily == AddressFamily.InterNetwork)
                    {
                        ip = item;
                    }
                }

                var client = new WebClient();

                var values = new NameValueCollection();
                values.Add("Guid", guid.ToString());
                values.Add("IP", ip.ToString());
                values.Add("Data", text);

                var bytes = await client.UploadValuesTaskAsync(uri, values);
                return bytes;
            }
        }
        catch(Exception err)
        {
            Console.Error.WriteLine(err.Message);
            return null;
        }
    }
}

public class HomeController : Controller
{
    [HttpGet]
    public IActionResult Task(Guid id)
    {
        return Ok();
    }

    [HttpPost]
    public IActionResult Task(NameValueCollection data)
    {
        if (ModelState.IsValid)
        {
            var count = data.Count; // 0
            return Ok();
        }
        else
        {
            return BadRequest();
        }
    }
}