You're going to need to figure out the required settings for the VPN server you're working with, whether you use the standard client or some add-on. That information is a prerequisite for a VPN client; for any VPN client.
If the standard VPN client present in OS X doesn't and cannot be gotten to work, then something like IPSecuritas or the OpenVPN client would be a typical fallback choice, but IPSecuritas is far more flexible — which means far more complex. These clients are available as application downloads; no Brew or MacPorts required.
Is this your server you're connecting into? Or is somebody else controlling it?
If it's your server and thus your VPN server, then you'll have the option to get either the VPN server in the gateway firewall box or the VPN server running in the target system configured to allow the OS X VPN client to work.
If the server is controlled by somebody else, ask them for the settings necessary for the VPN client.
As Barney-15E states, using Brew or MacPorts won't help, unless you're installing the VPN client that way — which would be a little unusual — and you're still going to have to figure out the L2TP / IPSec or PPTP or other settings here, irrespective of how the VPN client gets installed.
