A £5 wireless dongle gets around the Ethernet soluton and would allow connection to BTWifi or any other wireless networks that he can get the password for. It would also allow tethering to a mobile phone should he have one.
Parental controls on the device can be gotten around fairly easily such as setting up another user account or using VPN etc etc .
I want to block internet access to my sons computer and phone, and have used BT Access Control on the Bt Home Hub. However, he's abit of a computer geek and I think he may have got around it as there are lots of new devices been added since blocked it. Can he get around it by changing something on his computer if it's blocked? If so, how can I stop this?
Have been through similar experiences with my own son several years ago and had many battles to make sure homework and exam revision got done. I tried my best to encourage other interests, part time jobs etc. A very difficult and worrying time. Turned out he was spending time online teaching himself different programming languages and developing computer games. Now he's earned money developing online games and is part way through a degree in computer science.
If your son has a passion and talent for computing then why not encourage it as a career aim but point out that he needs to also find some other interests and skills to build up a cv.
Trouble is my son is not in the slightest bit interested in sorting any BT Smart Hub issues and tells me to buy something better instead!
Apologies if I am way off track from the main question but your issue seems similar to the one I had.