Currently Being ModeratedJan 9, 2013 6:10 AM (in response to MachineHead119)
According to this Apple document
you don't have (all) the correct ports open. Specifically you say UDP 1700 the document says UDP 1701 — for L2TP.
Also it would be beneficial to save the configuration file in the server app and then mail it to your client machines, they can then import it. Will help to ensure client machines have your specific setup.
Let us know how you go.Mac mini, OS X Server
Currently Being ModeratedJan 9, 2013 3:25 PM (in response to FromOZ)
Thanks FromOZ, sorry, typo its supposed to be 1701. I just checked the rest of the document for typos haha..thank you for the reply!
Back to the drawing board
Currently Being ModeratedJan 10, 2013 7:57 AM (in response to MachineHead119)
Try saving the configuration file and push it out to clients, that way you know they are running the config expected by the server VPN.
Then look at log files on server while a client tries to connect and see if there is any enlightenment there.
Look at log files on the client.
If you get really stuck you could run a network sniffer tool — WireShark is good and has OS X app — to see what is happening on the client during it's attempts to connect.
Good luck! If you get it solved please come back and advise what was solution for next person who perhaps gets in same trouble.