Ipv6 app rejected xamarin

Question

my app was rejected by apple with this message:

..We discovered one or more bugs in your app when reviewed on iPad and iPhone running iOS 10.2 on Wi-Fi connected to an IPv6 network.

Specifically, no action occurred when we attempted to create an account..

this is what i do in my registration page:

if (!EQiOS.Reachability.Reachability.IsHostReachable(myurl)) 
                {
                    UIAlertView alert = new UIAlertView()
                    {
                        Title = "Oops!",
                        Message = "Purtroppo sembra che non ci sia connessione, attiva la rete, se il problema persiste non esitare a contattarci!"
                    };
                    alert.AddButton("OK");
                    alert.Show();

                }

first of all i'm checking if there is connection and then :

i'm using this to update the user on my db

string check = msql.updateData(url);

it connects to a php page

this is the method

#region UPDATE_DATA
        public string updateData(string url) {


            var request = System.Net.HttpWebRequest.Create(url);

            request.Method = System.Net.WebRequestMethods.Http.Get;

            var response = request.GetResponse();

            System.IO.StreamReader str = new System.IO.StreamReader(response.GetResponseStream());

            return str.ReadToEnd();
        }
        #endregion

and this is for reading data on my server :

public List<List<string>> GetTable(string url, string nome_array, List<string> array_col)
        {

            string elemento_name = nome_array;

            int fine = array_col.Count;
            Console.WriteLine(fine);


            var multiDimensionalArr = new List<List<string>>(); // CREO LISTA MULTIDIMENSIONALE DI TIPO STRINGA CHE CONTERRA' LA TABELLA RISULTANTE


            WebClient client = new WebClient(); // INIZIALIZZO CLIENT WEB

            string value = client.DownloadString(url); //JSON IN STRINGA VALUE

            Newtonsoft.Json.Linq.JObject jObject = Newtonsoft.Json.Linq.JObject.Parse(value); //DESERIALIZZO JSON


            int i = 0; //VARIABILI PER IL CONTEGGIO ELEMENTI
            int j = 0; //VARIABILI PER IL CONTEGGIO ELEMENTI

            foreach (var item in jObject[elemento_name])  //PER OGNI ELEMENTO ESISTENTE NELL'ARRAY
            {
                multiDimensionalArr.Add(new List<string>()); //CREO NUOVA RIGA NELL'ARRAY

                do
                {
                    multiDimensionalArr[i].Add(Convert.ToString(jObject[elemento_name][i][array_col[j]])); // AGGIORNO ARRAY CON ELEMENTO CORRISPONDENDE
                    j++;
                } while (j < fine);


                j = 0;
                i++;
            }

            return multiDimensionalArr;

        }

where is the problem? i think that it should be because sometimes my app crashes with ReadDone2 Failure but i don't know if this is the problem.. and if not apple will reject my app for that?