string host = Dns.GetHostName();
var client = new TcpClient(host, 13);
using (var streamReader = new StreamReader(client.GetStream()))
{
var response = streamReader.ReadToEnd();
var utcDateTimeString = response.Substring(7, 17);
var localDateTime = DateTime.ParseExact(utcDateTimeString, "yy-MM-dd hh:mm:ss", CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal);
TextBox1.Text = localDateTime.ToString();
}