Hello Rollerpig69,

We understand that  you would like to manage the connected devices and monitor you’re childs usage for internet so, make sure that the device that you are trying to block internet for your child need to be first connected to the WIFI, we do have an option on the web  interphase to disable the WIFI for a particular period of time and days .

To proceed with it follow the link below :

http://arris.force.com/consumers/articles/General_FAQs/SVG2482AC-Parental-Control-Block-Services-Applications

Let us know if this helps .