While setting up a Report Server to run with SSL, one of my customers repeatedly got the following error message:

"The underlying connection was closed: Could not establish trust relationship with
remote server

The interesting thing was that the /Reports folder worked fine, it was just /ReportServer that threw the exception above.

We followed the standard SSL/SSRS troubleshooting steps:

In rsReportServer.Config:

In rsWebApplication.config:

Still, no joy...finally, we checked the cert associated with our Vdirs, and saw that it was created for domain.com versus machine.domain.com. Since we were just testing, we regenerated the cert to reflect machine.domain.com and we were good to go.