For more information about the VPN service and instructions on how to install these files please go to https://www.ch.cam.ac.uk/computing/openvpn-service.
Most people will want one of the options from this section. These configurations will attempt to send traffic for the University network via the VPN, and everything else via your usual network connection.
These are only for use if you find the VPN is blocked on the network you are connected to, or you are having network issues. They use an alternative protocol which is slower but more reliable, and unlikely to be blocked.
These send all your traffic via the VPN and so can be slower than the standard config files. They are useful if you need to access resources outside the University network that use IP-based access control.
These are specialist files for use with unusual clients, or in unusual situations. Most people won't need these.