I found this:
Pausing a device blocks it from accessing the Internet when connected to your home network. In-progress activity might not stop immediately. Access to local network devices (like printers) and connections that use cellular data or other WiFi networks won't be paused.
To pause an individual device simply select the device and then select Pause Device. You can either pause the device for a specific amount of time (for example, 30 minutes, one hour or two hours) or indefinitely until you choose to unpause the device.
When attempting to access the Internet on a paused device, the user will see the device's default message that the site cannot be reached or that it is not connected to the Internet.
Note: If you've previously set up a device block from your Gateway's Admin Tool (http://10.0.0.1), you should see the device listed with a pause icon in xFi indicating WiFi access over your home network is already paused. Once you Pause/Unpause a device or access Bedtime Mode or Port Forwarding through xFi, you will no longer be able to access similar features (block, scheduled block or port forwarding) through the Gateway's Admin Tool (http://10.0.0.1)."