Take it your trying to get to SSMS to connect to the SSRS instance.  IIFC that uses RPC so you need to allow the full RPC port numbers which is pretty much every port which is a security risk as you expose a lot about the server in doing so.  I've not found a way to limit the RPC port for SSRS yet.  So if your security/network teams say OK you can do it otherwise, the solution is to remote into the machine and run SSMS from there.