We use ARCgis enterprise 11.3. We have two servers, a main data server that controls all GIS functions and an ARC web adaptor server. The main GIS server lives on our internal network behind our firewall. This server gives information to the web adapter server which lives on the DMZ interface of the same firewall. There are several third party applications at our organization that use maps presented from the ARC web adapter server. These maps that are rendered/embedded from the web adapter server that were up until about mid to late March of this year working just fine. There have have been no major changes to our network infrastructure in this time. In these third party applications when the third party applications now try to interface with the web adapter to render the maps the maps sometimes do not load at all. The rest services from the web adapter are advertising properly. I have fixed the problem temporarily by just clearing the browser cache. However if exit the third party application and go back in, the maps do not render and the clearing the browser cache does not work.
ARC support is of course saying it is the third party applications. I am not convinced it is. Any ideas would be appreciated.
Do the maps render within Esri applications coming from the web adaptor? If you're able to test that, then you can isolate it to being a problem with Esri vs. the third party applications.
What I perceive is that there is a web server which is running IIS and that is where the ArcGIS Web adaptor for ArcGIS Server is installed and configured. On this web server there are 3rd party apps that are also hosted.
I would look into the ports being used by the 3rd party applications and ensure the Esri related applications are in their own application pools. Just installing the web adaptor ArcGIS Server can be a hassle if you are hosting several third-party applications on the same machine.
Action items:
Sharing levels for the maps being published. There was mention of this, but if you have to sign into view something this means the sharing of that service or map is set to organization or owner. It might just need to be shared publicly.
Check the ports being used by the 3rd party apps and change them to another port that isn't being consumed by the Esri applications.
Going deeper. Ensure you are not just dropping everything into a default application pool.