Just for reference, this is the wiki page that describes VPN in LMCE (http://wiki.linuxmce.org/index.php/VPN
). I'm sure most of you have read it already, though.
There are some gotchas in there as well, for instance this
Note: Currently you need to re-enable the user and change his username after any change to the Network settings page as the files are rewritten
Also, messing around with forwarding network ports without understanding how VPN works can be a big security problem:
Do NOT forward port 1701 (L2TP), this would have allowed direct access to the L2TP server, bypassing IPSEC entirely and sending all your data unencrypted. The whole idea is that the IPSEC connection encrypts your data from end to end, and on the server end, this data will be passed on to port 1701 internally.
It *is* easier to get a connection when not going through IPSEC, but some devices will happily connect to the L2TP server if the IPSEC fails for some reason.
That said, my biggest hurdle getting VPN set up was to configure other network routers in the path (my broadband router) properly. This was mostly a try-and-fail history until I got the correct setting. Any setting related to IPSEC should be tried in all their possible settings (I had to turn one IPSEC setting off to get mine working). It seems to me that IPSEC is the cause of most problems with this VPN, so that is where I would do my investigations.
And in one case I was unable to get VPN working from one particular network because of the router at that site (or possibly other network limitation at that site).
If you have any concrete questions I can try to answer them.