I managed to take down an entire school network with one VPN.

In short, I ran a personal VPN and eventually the System Administrators at my old school managed to pick it up as unknown traffic. For some reason, they managed to block the port but not the IP so I changed the port to 443 and their automatic system blocked port 443 on their entire network essentially rendering HTTPS useless for a few hours.

I never got approached about it but my school invested in a new IT team.