Through help pages for serverscan Esri encourage users to disable the ArcGIS Server REST services directory.
Users browsing ArcGIS Enterprise are offered links to this services directory from the ArcGIS Enterprise Portal content item page.
Clicking the hyperlinked name of the Layer or selecting “View” beside the URL title both launch the ArcGIS REST services directory for the service.
When ArcGIS Server REST service directory browsing is disabled the user is presented with a 403 response page
This response can be confusing for users less familiar with GIS and/or the ArcGIS architecture as they are following default links presented to them within ArcGIS Enterprise, and despite the fact that the url is valid, the 403 warning does not make this clear to them.
It would be valuable if an organisation had the ability to replace this 403 response page with a custom page which provided details of how to use an ArcGIS Server REST service url. The ability to add the organisation logo, and some custom text (dynamic or static) could make this page more user friendly. This in turn would help to avoid users feeling like they have made a mistake, and instead it rewards them for their curiosity and interest.