Please help me prevent my teenage daughter from bypassing my parental control and downtime

My daughter I'm just learning has been sneaking onto the wifi internet and is using some kind of VPN and she's on it offline and I can't stand disobedient behavior. I can't find out what her assigned device has been up to now that I know she's been deceitful for over a month and a half I'm 56 years old and very much clueless of the technology and VPN and I don't like it. 

Please 🙏 someone respond