Xamarin HttpClient.PostAsync deadlock

Question

We are having issue with System.Net.Http.HttpClient class. The code mentioned below is working fine with many Android devices except some, out of which two devices are listed below. The execution gets stuck on following line blocking the thread that makes app unresponsive resulting in raising ANR (Application Not Responding).

var resp = await client.PostAsync(url, content);

Impacted devices: Samsung Note 9 (Android 9.0) and Samsung S7 (Android 8.0)

Recently we have updated some dependencies that were required for updating Google Maps and SMS Retriever API.

Here is the source code:

async void ExecuteLogin()
        {
            try
            {

                var isOperationSuccessful = await PerformServiceCall(async () =>
                {
                    await DependencyService.Get<DataStore.Abstractions.IAuthService>().LoginAsync(Username, Password.Encrypt());
                });
            }
            catch (Exception ex)
            {
            }
            finally
            {
            }
        } 


public async Task LoginAsync(string username, string password)
        {
            var response = await PostHelper.DoRequest<LoginRequest, LoginResponse>(ServiceURL.Login,
                new LoginRequest()
                {
                    UserId = username,
                    Password = password,
                });

            ApiResponseValidator.ValidateResponse(response, "Unable to login");

            GlobalHelper.SessionId = response?.SessionId;
            GlobalHelper.Username = username;
        } 




public static async Task<U> DoRequest<T,U>(string url, T obj)
        {
            var result = "{}";
            try
            {
                using (var client = new HttpClient())
                {
                    string datasent = JsonConvert.SerializeObject(obj);
                    HttpContent content = new StringContent(datasent,
                        Encoding.UTF8,
                        "application/json");
                    client.DefaultRequestHeaders.Add("user-agent", "Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2; WOW64; Trident / 6.0)");

                    var resp = await client.PostAsync(url, content);
                    
                    result = resp.Content.ReadAsStringAsync().Result;

                    return JsonConvert.DeserializeObject<U>(result);
                }
            }
            catch (Exception ex)
            {
                throw new Exception($"Unable to service the request at this time. {ex.Message}", ex);
            }
        } 

protected async Task<bool> PerformServiceCall(Func<Task> serviceCallAction, 
            Action<GenericException> onError = null)
        {
            if (!CrossConnectivity.Current.IsConnected)
            {
                DisplayInfo("Looks like you're not connected to the internet.", "DISMISS", null);

                return false;
            }

            if (IsLoading)
            {
                return false;
            }

            try
            {
                IsLoading = true;
                await serviceCallAction?.Invoke();
                return true;
            }
            catch (GenericException ex) when (ex.ExType == ExceptionType.SessionTimeOut)
            {
                SessionTimedOut<BaseViewModel>();
                Logger.Report(ex, Severity.Error);
                return false;
            }
            catch (CriticalException ex)
            {
                if (onError != null)
                {
                    onError.Invoke(ex);
                }
                else
                {
                    DisplayCriticalInfo(ex.Title, ex.Message);
                }
                                
                Logger.Report(ex, Severity.Error);
                return false;
            }
            catch (GenericException ex)
            {
                if (onError != null)
                {
                    onError.Invoke(ex);
                }
                else
                {
                    DisplayInfo(ex.Message);
                }

                Logger.Report(ex, Severity.Error);
                return false;
            }
            catch (Exception ex)
            {
                DisplayInfo(ex.Message);
                Logger.Report(ex, Severity.Error);
                return false;
            }
            finally
            {
                IsLoading = false;
            }
        }

Here is the list of packages with their version for your reference defined in packages.config in Xamarin project.

<package id="ExifLib.PCL" version="1.0.1" targetFramework="portable-net45+win+wpa81+MonoAndroid10+xamarinios10+MonoTouch10" />
  <package id="Microsoft.Bcl" version="1.1.10" targetFramework="portable45-net45+win8+wpa81" />
  <package id="Microsoft.Bcl.Build" version="1.0.21" targetFramework="portable45-net45+win8+wpa81" />
  <package id="Microsoft.Net.Http" version="2.2.29" targetFramework="portable45-net45+win8+wpa81" />
  <package id="Newtonsoft.Json" version="9.0.1" targetFramework="portable45-net45+win8+wpa81" />
  <package id="Plugin.Fingerprint" version="1.4.9" targetFramework="portable45-net45+win8+wpa81" />
  <package id="Plugin.Permissions" version="2.0.1" targetFramework="portable45-net45+win8+wpa81" />
  <package id="sameerIOTApps.Plugin.SecureStorage" version="1.2.1" targetFramework="portable45-net45+win8+wpa81" />
  <package id="Syncfusion.Xamarin.SfCalendar" version="14.3.0.49" targetFramework="portable45-net45+win8+wpa81" />
  <package id="Xam.Plugin.Connectivity" version="2.3.0" targetFramework="portable45-net45+win8+wpa81" />
  <package id="Xam.Plugin.Geolocator" version="3.0.4" targetFramework="portable45-net45+win8+wpa81" />
  <package id="Xamarin.Build.Download" version="0.4.6" targetFramework="portable45-net45+win8+wpa81" />
  <package id="Xamarin.Forms" version="3.2.0.871581" targetFramework="portable45-net45+win8+wpa81" />
  <package id="Xamarin.Forms.CarouselView" version="2.3.0-pre2" targetFramework="portable45-net45+win8+wpa81" />
  <package id="Xamarin.Forms.GoogleMaps" version="3.0.4" targetFramework="portable45-net45+win8+wpa81" />
  <package id="Xamarin.Forms.Maps" version="2.3.4.247" targetFramework="portable45-net45+win8+wpa81" />
  <package id="Xamvvm.Forms" version="1.0.0" targetFramework="portable45-net45+win8+wpa81" />
  <package id="XLabs.Core" version="2.2.0-pre02" targetFramework="portable45-net45+win8+wpa81" />
  <package id="XLabs.Forms" version="2.2.0-pre02" targetFramework="portable45-net45+win8+wpa81" />
  <package id="XLabs.IoC" version="2.2.0-pre02" targetFramework="portable45-net45+win8+wpa81" />
  <package id="XLabs.Platform" version="2.2.0-pre02" targetFramework="portable45-net45+win8+wpa81" />
  <package id="XLabs.Serialization" version="2.2.0-pre02" targetFramework="portable45-net45+win8+wpa81" />