Currently Being ModeratedNov 13, 2012 10:45 AM (in response to Mac OS 9000)
I've had problems connecting L2TP VPN from my Mountain Lion Macbook Pro to a MacMini running 10.7 Server. Port 500 was initially forwarded UDP only and making it TCP/UDP fixed the problem. No idea why but it was a fluke that I found it.
Currently Being ModeratedSep 13, 2013 6:22 PM (in response to Mac OS 9000)
I found this page based on my searching, and due to the exact same problem as you Mac OS 9000.
I hope you've got it working now.
To get my Snow Leopard Server VPN visible to the Internet besides just the LAN — no matter what sort of ports and protocols I allowed through — didn't seem to work.
Go to Firewall Settings > DMZ Host > and enter the IP address of your server. (I'm assuming -- and for the benefit of others -- you've set up the DHCP IP address for your server to be statically set by the Actiontec router.)