HTTP Error 503. The service is unavailable. error when trying to view a power bi report

I figured out what my issue was!  Thanks to a previous reply for making me think about this!

I had a new IP address added to the server for PBIRS.  I also had a DNS name added for that IP so users could access it with a friendly name, e.g., reporting.abc.com/reports instead of 10.x.x.x/reports.  I also had a redirect setup in IIS that would send users from reporting.abc.com to reporting.abc.com/reports just to keep the user-facing URL as simple as possible.  When I access the portal using the DNS name (reporting.abc.com) (causes IIS redirect) and run the report I would get this error.  However, if I access the portal using the full portal URL with IP address (10.x.x.x/reports) (does not cause IIS redirect) and run the report I would NOT get the error.  I deleted the site from IIS since I was only using IIS for redirection.  If I access the portal using the full portal URL with DNS name (reporting.abc.com/reports) (does not cause IIS redirect) and run the report I would NOT get the error.

I relize this may not be the normal implementation, but HTTP Redirect was the root cause of my issue.  I hope this helps someone in the future.