IPhone 4S 5.1.1 b206 failed to connect to L2TP VPN (Mac OSX 10.6.8)

Question

I just upgraded my iPhone 4S from 5.0.1 to 5.1.1 b206, and I noticed this issue.
I have a Mac Mini Server running Mac OSX 10.6.8.
I build up the VPN server with L2TP and PPTP.
Before I upgrade my iPhone to 5.1.1, it works with L2TP and PPTP both.
After I upgrade to 5.1.1 b206, it only connect to PPTP, L2TP shows the error message
"VPN Connection"
"The L2TP-VPN server did not respond. Try reconnecting. If the problem continues, verify your settings and contact your Administrator."
Simultaneously, I tried my iPad, it connects to L2TP AND PPTP with no problem.
Please advice, thanks.

Answer 1

The point of checking the console, is there might be a message that pops up in response to trying to copy a file to the target. Your looking for a doorbell like response. IE you try to copy a 1k file, error message pops up. Try to copy again, same error message.
Is Copy Enabled on the target client?
ie: ard into the target, open system preferences, click on sharing, click on remote management. ( If allow access is set to "only these users"; then select the account your using to ard into the computer. ) click on the options button, Verify the fallowing items are checked: Open & Quite Applications, Change Settings, Delete & Replace Items, Restart & Shutdown, Copy Items. click the Ok button.
if Copy Is Enabled, have you verified the firewall is off?
ie: ard into the client, open system preferences, click on security, click on the Firewall tab, verify Firewall is off. This would also go for any programs that act like a firewall. (little snitch, anti virus barrier, extra)
Have you verified the ARD reporting time on the target computer? Some times ARD can get weird if the reports have ran in a while.
ie: get info on the client in ARD. click on the reporting tab. Set the reporting time to be a few minutes from the actual time. Let the time on the target computer hit the reporting time.Then try copying a file.
Have you ruled out the network?
ie: plug the ARD computer into the target directly by ethernet. make sure airport is off on both computers. Then try copying the file again.