Silverlight timeout exceptions started in El Capitan when calling WCF services

Howdi,

I'm trying to run my beloved Silverlight application on the newest Mac version 10.11.1 (release).

Problem is, my beloved application consumes data through RIA services as well as other "native" WCF services, but when running OOB most of the calls fail with this kind of exception:

System.TimeoutException: [HttpRequestTimedOutWithoutDetail]

Arguments: http://srvauto3/DigitalManager/WCFDPMService.svc

Debugging resource strings are unavailable. Often the key and arguments provide sufficient information to diagnose the problem. See http://go.microsoft.com/fwlink/?linkid=106663&Version=5.1.40728.00&File=System.S erviceModel.dll&Key=HttpRequestTimedOutWithoutDetail ---> System.Net.WebException ---> System.Net.WebException

at System.Net.Browser.BrowserHttpWebRequest.InternalEndGetResponse(IAsyncResult asyncResult)

at System.Net.Browser.BrowserHttpWebRequest.<>c__DisplayClassa.<EndGetResponse>b__ 9(Object sendState)

at System.Net.Browser.AsyncHelper.<>c__DisplayClass4.<BeginOnUI>b__0(Object sendState)

--- End of inner exception stack trace ---

at System.Net.Browser.AsyncHelper.BeginOnUI(SendOrPostCallback beginMethod, Object state)

at System.Net.Browser.BrowserHttpWebRequest.EndGetResponse(IAsyncResult asyncResult)

at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelA syncRequest.CompleteGetResponse(IAsyncResult result)

--- End of inner exception stack trace ---

at System.ServiceModel.AsyncResult.End[TAsyncResult](IAsyncResult result)

at System.ServiceModel.Channels.ServiceChannel.EndCall(String action, Object[] outs, IAsyncResult result)

at System.ServiceModel.ClientBase`1.ChannelBase`1.EndInvoke(String methodName, Object[] args, IAsyncResult result)

at ServiceClients.DPM.WCFDPMService.WCFDPMServiceClient.WCFDPMServiceClientChannel .EndCreateDigitalView(IAsyncResult result)

at ServiceClients.DPM.WCFDPMService.WCFDPMServiceClient.ServiceClients.DPM.WCFDPMS ervice.IWCFDPMService.EndCreateDigitalView(IAsyncResult result)

at ServiceClients.DPM.WCFDPMService.WCFDPMServiceClient.OnEndCreateDigitalView(IAs yncResult result)

at System.ServiceModel.ClientBase`1.OnAsyncCallCompleted(IAsyncResult result) [ServiceClients.DMP.MonitorProxyWrapper::OnCreateDigitalViewCompleted()]"

Note that this happens ONLY when running OOB (out of browser) - inside the browser everything works as before.

But since I have important features that requires the elevated trust of OOB mode, I can't run it in-browser.

By using WireShark I realized that there is a significant delay between the call to the async request in the application, and when the packets are actually being sent on the wire (can be 30 seconds and above).

I would be glad for any suggestion as to what's the causes of this, or how to advance in my inquiry?

Many thanks,

Ziev