How do I find VPN details and how do I block VPN?


I know my child is using a VPN to get around Koalasafe but I don’t know how to find what VPN he is using, and once I find it I don’t know how to block it. Please could you give me a step by step guide as to what to do as it is currently rendering Koalasafe completely useless… Blocking the VPN “Category” does not seem to help stop him.