HTTP 404 error for Browser users on Report Server

We have installed PowerBI Report Server.  So far we have made the following progress:

- App server and DB servers implemented

- WAP server for authentication connected

- Admin users can connect, load reports and view reports

Now we have the following problem:

- Browser users can be authenticated to be given access to the Report Server

- But they cannot see reports

- Security settings have been given to them

- http 404 error appears, and loading data just keeps running

One support team (non-expert) believes it is related to CatalogItems or maybe IP Address binding.  Any guidance is most appreciated!