VPN just stopped working again!!!

Question

I have had VPN working fine both internally (without going through a router) and also from external Pcs and Macs. This was working fine, until came back into office after weekend and the server had dropped all connections including AFP. Rebooting the clients for the AFP resolved this side of things but the VPN service now has the error "The L2TP-VPN server did not respond. Try reconnecting. If problem continues verify your settings and contact your Administrator" I get this from both internal and external clients. So Im sure its not a router problem.
I had a probelm before with the PPTP connection, this again came about after working fine for ages... I solved this and then the VPN ws working fine until the L2TP-VPN error appeared.
Im not really sure where to look tbh with regards this... there have been no changes to routers, and in fact the internal VPN connections I had working dont use the router anyway. The external PCs that had a connection were using the PPTP protocol and now they cant connect either so it seems to be a general failure. Although I can get a connection for a short time using my iPhone VPN but this drops off after about a minute, and doesnt allow me to connect to any servers on network, which I could do before when it was all working fine.
Im at a loss with this VPN and hope that someone somewhere out there can help with this. Do Apple read these posts I wonder?
Cheers

Answer 1

I found a TEMPORARY solution.
The short answer: "hard code" all DNS servers. No Automatic configurations.
I have observed that traffic is still route-able over the regular internet connection and to the remote network being accessed via Cisco IPSEC, only DNS is hurt!
To fix this you will have to "hard code" all DNS servers in your network configuration, DHCP and other automatic configurations will be ignored!
On the plus side, you will have all the IP addresses you need will be in your network interface's config as "soft" in a light grey font.
To get to a typical DNS configuration for an interface you will go into System Settings -> Network -> Click on a required interface --> Advanced button and then finally there will be a DNS tab. All you need to do is put that nice and soft IP address in by clicking the "+" button.
If your in a bit of a BIND, for a public DNS server (On your Airport or Ethernet interfaces) may I recommend Google's DNS server at 8.8.8.8 because it is very easy to remember. This will allow you to speed up your configuration by not having to even think of "192.168.0.1","10.0.0.1" or "234.245.12.333". (Good luck with that last one!)
Possibly Optional:
And as for your VPN interface, you will need to add your super secret domains into the "Search Domains" box by clicking on the "+". I have observed some odd behavior with adding these.
If you have issues with the above, you should setup a resolver configuration.
To do this you will have to do the following:
- Open up the terminal, type "sudo bash" and then enter your password.
- Make a directory with "mkdir /etc/resolver"
- Change the current directory to resolver with "cd /etc/resolver"
- Now you will have to create a file for each domain on the VPN you wish to access (yes pain, thankfully I only have a couple to setup). For this example I will use the domain "foo.com", so create the file by typing in "nano foo.com".
- Now fill the file with the following (note the almost bogus IP address) :
domain foo.com
nameserver 8.8.8.8 <-- change to your VPN's DNS server
- Hit "Control+x" to save and exit.
And then you should be OK.
It isn't ideal, but it is working for me at the moment.
BONUS:
Hopefully your host list isn't long, Edit /etc/hosts:
Company hostnames that exist on the public internet you will want to specify in your hosts file.
ie:
mail.your-company-email-hosted-by-google.com
VPN endpoints
Any other site you need outside the VPN
The reason for doing this is once you connect to vpnendpoint.foo.com, you may not be able to resolve it again because of the resolver config or the OS X DNS configuration. So re-connecting to the VPN without rebooting will be impossible, and in one case where I used the raw IP instead of a hostname!
Apple: you're not off the hook, please fix so we don't have to do this crap!
OH, and fix the **** key management issue! I am sick of re-entering my passwords and keys!!