sql server: configure SSRS remotely: a connection to the computer can not be established

I just installed the new SQL Server Reporting Services 2017 following these instructions:

I have a Windows server with SQL Server Express 2017.

I need to set up the report server remotely, but when I try to find the server from the Report Server Configuration Manager, it simply says that I can not establish a connection to the computer & # 39; (view image).

Report Server Configuration Manager

I tested this configuration on two separate computers outside the domain (to configure remotely), and it worked fine, but it does not work on the server that is inside the domain.

I added my user for permissions with these steps here:

But it still does not connect, any idea of ​​what's missing?

I also looked at this question, but I could not find much help:

Unable to sign in to Reporting Services through SSMS and the Reporting Services configuration administrator