I have downloaded a VPN service app, and it works fine. However, if I run on school WiFi, VPN hangs on "Connecting..." and after 10 seconds it disconnects and tries again. I believe this is a WiFi problem, but I don't know for sure.
Most schools have firewalls on their network that prevent VPNs from being used. This is because firewall website filtering can be usually bypassed by using a VPN.
So as you guessed, it is something on the network that’s blocking the VPN.
And just so you know I have not found a way to bypass a VPN blocker or firewall(I am also a student at a school with a similar firewall)
Use Psiphon, it is a vpn designed to bypass firewalls. It works at my school.