Deploying Watson Chat on IIS

So I've created a simple ASP .NET site, where you can send a message to the Watson service and receive the response.

It works locally when I run the application from VS2017, but now I've deployed it to my 2012 R2 Server and it doesn't work. The application runs, but I'm not able to receive any answer from the Watson service.

What am I missing in the IIS?

This is the SDK, I've been using.

https://github.com/watson-developer-cloud/dotnet-standard-sdk

Here is the only error I can find in the eventvwr.

Event code: 3005 
Event message: An unhandled exception has occurred. 
Event time: 25-04-2019 15:51:35 
Event time (UTC): 25-04-2019 13:51:35 
Event ID: 8eb66320f2fa412ea0a2cf3f61d5f3b2 
Event sequence: 19 
Event occurrence: 1 
Event detail code: 0 

Application information: 
    Application domain: /LM/W3SVC/6/ROOT-6-132006738849963250 
    Trust level: Full 
    Application Virtual Path: / 
    Application Path: xxx
    Machine name: OSI4908 

Process information: 
    Process ID: 6844 
    Process name: w3wp.exe 
    Account name: NT AUTHORITY\NETWORK SERVICE 

Exception information: 
    Exception type: HttpException 
    Exception message: The remote host closed the connection. The error code is 0x80070057.
   at System.Web.Hosting.IIS7WorkerRequest.RaiseCommunicationError(Int32 result, Boolean throwOnDisconnect)
   at System.Web.Hosting.IIS7WorkerRequest.ExplicitFlush()
   at System.Web.HttpResponse.Flush(Boolean finalFlush, Boolean async)
   at System.Web.HttpWriter.WriteFromStream(Byte[] data, Int32 offset, Int32 size)
   at Microsoft.Owin.Host.SystemWeb.CallStreams.OutputStream.Write(Byte[] buffer, Int32 offset, Int32 count)
   at Microsoft.AspNet.SignalR.Owin.ServerResponse.Write(ArraySegment`1 data)
   at Microsoft.AspNet.SignalR.Hosting.ResponseExtensions.End(IResponse response, String data)
   at Microsoft.Owin.Mapping.MapMiddleware.<Invoke>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.StageAsyncResult.End(IAsyncResult ar)
   at System.Web.HttpApplication.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step)
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)