No such host is known HttpClient

[hadinajafi1984]

با سلام
من توی کد برنامه از طریق یه action چند تا api رو کال میکنم ولی بعضی وقتا این ارور رو میده : No such host is known
اینم کد برای کال کردن API ها :

 public async Task<List<T>> Get(string getAsyncUrl, string apiKey = "", string token = null)

        {

            client = new HttpClient

            {

                BaseAddress = new Uri(BaseUrl)

            };

           

            client.DefaultRequestHeaders.Clear();

            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            client.DefaultRequestHeaders.Add("api-key", apiKey);

            if (token != null)

            {

                client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);





            }

            var res = await client.GetAsync(getAsyncUrl);

            List<T> items = new List<T>();

            //Checking the response is successful or not which is sent using HttpClient  

            if (res.IsSuccessStatusCode)

            {

                //Storing the response details recieved from web api   

                var empResponse = res.Content.ReadAsStringAsync().Result;

                items = JsonConvert.DeserializeObject<List<T>>(empResponse  );

                return items;

            }

            else

            {

                var empResponse = res.Content.ReadAsStringAsync().Result;

                var error = JsonConvert.DeserializeObject<SystemMessaging>(emp  Response);

                throw new Exception(error.Message);

            }





        }