Most readers will probably find this post uninteresting - if you don’t know what a VPN is and aren’t interested in networking, tune out now!
OS X 10.5 comes with GUI configured clients for both PPTP and L2TP/IPSec VPNs. It also comes with a VPN server, in the form of the command line ‘vpnd’ program. Getting vpnd configured and running involves setting up a plist with the right settings and a few other small things. It’s possible to DIY, but if you want to save yourself the pain (and there can be a lot of pain involved), grab a copy of iVPN.
I have had countless issues getting the OS X 10.5 VPN clients to talk to the OS X 10.5 VPN server (vpnd), but after reading a tip on this Apple Support Discussions thread, I think I may have solved all of my remaining issues in one go (fingers crossed).
All I had to do was put the VPN client at the top of the “Service Order” list…
Setting the Service Order
To set the service order, go into your Network System Preferences pane, then click on the options “Gear Icon” at the bottom of the network devices list:
Now select “Set Service Order…”, drag your VPN(s) to the top of the list, hit OK, then hit Apply.
Hopefully, your VPN will now work as it’s supposed to!
Note that this tip will only make a difference if you can connect to your VPN, but are having problem accessing services on that network. If you can’t connect in the first place, the service order won’t make any difference.