TCP communication with step motor
I'm afraid that I don't know anything about TCP, but I did notice this. 


  if (!client.Connected)
  { /*ignore*/ }
  else
  {
     Console.WriteLine("Listener error: " + ex.Message);
  }



Instead of checking for the negative condition, check for the positive. It removes several lines of code and a comment. 

if(client.Connected)
{
    Console.WriteLine("Listener error: " + ex.Message);
}