Xamarin.android Post请求错误：NameResolutionFailure

[被遗忘者灬]

在虚拟机调试是正确的，可以获取到数据，打包安装到手机后就提示这个错误，不知道有没有前辈遇到过？
http请求方法：

   
public static async Task<string> SendPost(string url, Dictionary<string, string> param)
        {
            string result = "";
            StringBuilder postData = new StringBuilder();
            if (param != null && param.Count > 0)
            {
                foreach (var p in param)
                {
                    if (postData.Length > 0)
                    {
                        postData.Append("&");
                    }
                    postData.Append(p.Key);
                    postData.Append("=");
                    postData.Append(p.Value);
                }
            }
            byte[] byteData = Encoding.GetEncoding("UTF-8").GetBytes(postData.ToString());
            try
            {

                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
                request.ContentType = "application/x-www-form-urlencoded";
                request.Referer = url;
                request.Accept = "*/*";
                request.Timeout = 30 * 1000;
                request.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)";
                request.Method = "POST";
                request.ContentLength = byteData.Length;
                Stream stream = request.GetRequestStream();
                stream.Write(byteData, 0, byteData.Length);
                stream.Flush();
                stream.Close();
                HttpWebResponse response = (HttpWebResponse)(await request.GetResponseAsync());
                Stream backStream = response.GetResponseStream();
                StreamReader sr = new StreamReader(backStream, Encoding.GetEncoding("UTF-8"));
                result = sr.ReadToEnd();
                sr.Close();
                backStream.Close();
                response.Close();
                request.Abort();
            }
            catch (Exception ex)
            {
                throw ex;
            }
            return result;
        }

[被遗忘者灬]

没有添加INTERNET权限的原因！