Trying to restrict internet from accessing ****

Is he actually trying to play online, or access an Internet-enabled feature?

If he's trying to play over the Internet against others, he needs to have a Gold account.

If it's just within that title he's having issues, it could be a 2K Games restriction on online play -- for instance, EA does not allow accounts under 13 to play online. You might need to check with 2K if they have similar restriction on children playing
online.

I would love if it all access to the internet including live was restricted for people 18 and over.

I have the same issue or had..... make sure you the only person logged into your xbox one and try again. If someone is logged in and their internet access is restricted it effects you too. Hope this helps

Many Internet sites block access to known VPN technology to prevent the circumvention of their region restrictions so ditch it and use the normal connection.

If you have some sort of Access Control restrictions in place on your router (e.g. you can only access the Internet from 3-9pm) that may be causing your problem. I recently had an issue with my router (DIR-655) where a user was unable to connect due to Access
Controls being in place and the time on the router being incorrect. This was solved by setting the router up to automatically sync time with an Internet time server.