Block a device from app or remotely from a PC?

From the app you can "pause" a device, which I believe means it gets no internet and cannot communicate with any other devices on the Orbi LAN.

To administer the Orbi externally using the web interface, you must do one of two things from the web interface at home:

1. Enable "Remote Management", which is on the Orbi web interface, Advanced Tab, Advanced Setup, Remote Management.
   Once that is done, anyone who knows the admin password can connect to the Orbi as explained on the Remote Management web page.
   I would not do this unless the Orbi admin password is robust. As soon as the port is opened, hackers will attempt to login as "admin".
   With my 30 character password of Upper Case, Lower Case, Number, Symbols, and non-sense words, I calculate at one attempt per minute, it will take a hacker about 4 million years to try half of the possible combinations.  However, I am annoyed to see all of the invalid login attempts in the Orbi log file, so I turned it off.
2. Enable OpenVPN access on the Orbi.  This means that you can use an OpenVPN client remotely to access the Orbi network.  Once on the network you can use a web browser to open the Orbi web interface and administer it just as if you were at home.
   This requires signing up for a Dynamic DNS service, activating the VPN, and installing an OpenVPN client on a Windows, Mac, Linux, Android, or Apple device.

Both of these must be set up locally, so until you get home, only the Orbi "app" can do anything for you.