The connection keeps dropping

A tunnel that opens and then closes usually means the network underneath it is unstable or is interfering with VPN traffic. Move closer to your router or switch between Wi-Fi and mobile data to rule out signal problems. If it only drops on one network — an office, a school, a hotel — that network is probably filtering VPN traffic, and another server or country often gets through. On Android, also check that the system is not closing the app in the background.