Ok, so i've been struggling with this for 2 days so far and nothing i've found on the forum so far has quite answered my question.
I am currently running a Windows Server 2008 R2 box which requires 5 devices to connect to it.
I setup prior to now, a PPTP VPN into the server which was working perfectly fine.
Now with our team recently having acquired Apple and Android based mobile devices for remote working that are notoriously unhappy with PPTP connections I decided to change the config to L2TP which is more secure anyway and the mobile devices are happier with.
This is where my problems started.
I had no issues with the setup and changing the RRAS policy to L2TP/IPSEC and defining a pre-shared key.
I ensured the firewall was setup to allow inbound connections on Ports: 1701, UDP 500 & UDP 4500 (for NAT-T).
I then setup the same port forwarding on the router for the servers IP address.
I checked the services for the IKE and AuthIP IPSEC Keyring Module service & IPSEC Policy Agent to ensure they were started then set to automatic.
I then added the NAT-T registry fix as our server is behind an NAT based router.
None of this works. When connecting on Windows 7 and Vista Machines I get:
"Error 789 - The L2TP connection attempt failed because the security layer encountered a processing error during initial negotiations with the remote computer"
When trying to connect with a Mac, iPhone, iPad or Android phone I get:
Unsuccessful or Error the L2TP VPN Server did not respond.
I am quite fed up with this now as none of the prior suggestions seem to have worked but with the nature of the devices we are using I can't switch back to PPTP. Also to note though is that now PPTP does not work either even though I have not removed any of the settings or closed the ports on the server or router that it uses.
Can anyone shed some light on this?