All weekend I have been having trouble connecting to my work’s VPN on OS X 10.5 (Leopard). My favourite VPN client, Shimo, doesn’t even want to try, and the Cisco VPN client gives me this error:
Cisco VPN - Fix for Error 51: Unable to communicate with the VPN subsystem
All it is, is the Cisco VPN service needing a restart. Open a terminal and type:
$ sudo /System/Library/StartupItems/CiscoVPN/CiscoVPN restart