When using Stanford's VPN from home, we generally recommend using the Default Stanford split-tunnel VPN. To connect to the VPN from your Mac you need to install the Cisco An圜onnect VPN client.
Stanford's VPN allows you to connect to Stanford's network as if you were on campus, making access to restricted services possible. The built-in VPN client for Mac is another option but is more likely to suffer from disconnects. Cisco An圜onnect is the recommended VPN client for Mac.