Timeout to load ArcGIS Server hosted layers

I’m sharing a map and a geoprocessing service in ArcGIS Server. I configured the CMV(Configurable Map viewer) with the rest URLs to consume them. I deployed the CMV in a IIS server, then call the CMV in a iframe in my asp.net MVC 5 application.

When I’m running the CMV in local, the layers and the geoprocessing services are well loaded so usable. However when I’m running from my application it never loads and it gives me a timeout error.

I googled a bit and I found that I have to add this line in the web.config file, so the timeout would be extended :

<httpRuntime executionTimeout="21600" />

Yet nothing changes and the layers are not added to the map.
Do you know what may cause this issue right here?