Cannot connect to Orbi RBR 50 router remotely

This is correct.  There are two methods to access an Orbi router remotely:

• The Orbi 'app' provides a feature called Anywhere Access.  It must be enabled while connected to the Orbi locally.
  And, it is enabled only on the physical device that is running the Orbi app.  (I have four: two phones and two tablets.)
  Anywhere Access can be enabled on as many devices as you want, but has to be done when the device is connected locally.
• OpenVPN.  Netgear provides OpenVPN Host software on most of their routers.  Once set up, the user can load OpenVPN Client on lots of different devices (desktops, laptops, smartphones, tablets - Windows, Linux, Mac).
  Import the OpenVPN configuration created by the software.  This is explained on page 121 of the user manual:
  https://www.downloads.netgear.com/files/GDC/RBK50/Orbi_UM_EN.pdf 
  
  Compared to the Orbi app, OpenVPN can be challenging to get working.  Once set up, it provides access to the actual Orbi web interface, which is not really suitable for small screens (smartphones).
  
  This also has to be set up when connected locally to the router.  I validate that it is really working by creating a smartphone Hot Spot and connecting a laptop to the Hot Spot before leaving the room where the router is.