FritzReconnect.cs

namespace ReconnectFritz
{
    using System.IO;
    using System.Net;
    using System.Text;

    public class FritzReconnect
    {
        private string xmldata = "<?xml version=\"1.0\" encoding=\"utf-8\"?>" +
            "<s:Envelope s:encodingStyle=\"http://schemas.xmlsoap.org/soap/encoding/\" xmlns:s=\"http://schemas.xmlsoap.org/soap/envelope\">" +
                "<s:Body>" +
                    "<u:ForceTermination xmlns:u=\"urn:schemas-upnp-org:service:WANIPConnection:1\" />" +
                "</s:Body>" +
            "</s:Envelope>";

        public string ReconnectFritzBox()
        {
            string resulXmlFromWebService = null;

            var webRequest = WebRequest.Create("http://fritz.box:49000/igdupnp/control/WANIPConn1");
            var httpRequest = (HttpWebRequest)webRequest;
            httpRequest.Method = "POST";
            httpRequest.ContentType = "text/xml; charset=utf-8";
            httpRequest.Headers.Add("SOAPACTION", "urn:schemas-upnp-org:service:WANIPConnection:1#ForceTermination");
            httpRequest.ProtocolVersion = HttpVersion.Version11;
            httpRequest.Credentials = CredentialCache.DefaultCredentials;
            httpRequest.ContentLength = xmldata.Length;

            using (var requestStream = httpRequest.GetRequestStream())
            {
                //Create Stream and Complete Request             
                using (var streamWriter = new StreamWriter(requestStream, Encoding.ASCII))
                {
                    streamWriter.Write(xmldata);
                    streamWriter.Close();

                    //Get the Response    
                    var wr = (HttpWebResponse)httpRequest.GetResponse();
                    using (var srd = new StreamReader(wr.GetResponseStream()))
                    {
                        resulXmlFromWebService = srd.ReadToEnd();
                    }
                }
            }

            return resulXmlFromWebService;
        }
    }
}