Access an OLAP Cube out of the Network

I am wanting to enable the connection so that through excel, they can connect to the Analysis Services cubes that I have already processed on the server.

I'm following this tutorial, but I do not get anywhere:

  

link

I already made the Firewall configuration and nothing.

In summary , I need to know if it is possible for someone outside the Local Network to access my cubes connecting from Excel.

I look forward to your help!

Thanks