From that I would take it that someone manually reset back to factory default by pressing and holding the recessed button on the back
I may be wrong but I suspect that you have set access controls on the Homehub and somebody is resetting the hub to get around them. If that is the case there is no way to stop that from happening other than locking the hub away where it can not be reached.
The only sure way to stop access is to disconnect the router and lock it away. If you rely on software there is always a way around it and most kids know how to do it or at least know somebody who will be able to tell them how to do it.
You can't always get a second hand hub, disconnect existing hub and connect replacement providing nobody else is home which will give unlimited internet connection. When finished just reconnect existing hub and unless you checked connection time you would never know
just thinking like a teenager.😊
I'm sure you will sort it out. Keep in mind that if you remove his wireless devices he can always borrow a friends so you need to check the hub logs to see if any new devices that you are not aware of are connected.