My kid has figured out how to defeat any router based parental controls by simply enabling randomized MAC and forgetting and reconnecting to the network under a new mac that is not on the same Rules that was set previously. My solution for this was to upgrade my router to a Asus router that allowed me to create a Whitelist for MAC’s so in his attempt to Randomized the new mac isn’t on my whitelist so it can not connect to the network even if he has the password. Kind of wanted to avoid this because it does make connecting new devices a touch more difficult but I figure when guest are around I can enable guest network while they are around and disable it when they leave. And its not like we have a bunch of new Wi-Fi enabled electronics that we buy all the time so it isn’t too bad.

Now since this computer is a school based computer it is/or atleast should be so locked down that you can hardly do anything on it. My asus router does have controls to make family groups: Preschooler, School aged child 6-13, teen 13-18, and adult 18+. The family groups allows me to create individual profiles for each kid, when the internet will turn on for them and turn off. it will even go as far as to allow me to block what kind of content they are able to access so off bat porn, illegal and violence and gambeling has been blocked… but it goes as far as to list the following:
Internet telephony, Instant Messaging, virtual community, blog, mobile, file transfer, peer to peer, games, media streaming, internet radio. basically I mark the entire list when say they are grounded and should only get online for school purposes.

End of the day if he wanted to defeat the content filtering he could, my more primary concern was him trying to stay up until 3am playing a game and missing the bus. Which with the whitelist and shut off time that has helped alot. If monitoring content is the primary concern, the best method is to keep the PC in a communal area