Solved!
Still think that there was a problem with headers in the previous test but I solved it using another way (as always) see below.
public double GetTemperature(string address) { var request = (HttpWebRequest)WebRequest.Create(_url + address); request.Timeout = 3000; double returnTemperature = -99D; try { using (var stream = request.GetResponse().GetResponseStream()) using (var reader = new StreamReader(stream)) { char[] tempChar = new char[5]; reader.Read(tempChar, 0, 5); var temperature = new string(tempChar); ... } } }
Instead of "ReadToEnd" I am using the ordinary reader and in this specific case I only need the first few chars of the response.