Has anybody experienced problems with Windows Vista? We have hundreds of customers which successfully connect to our Cisco router from Windows XP. They manually (via wizard) create VPN-connection using their login, pswd and preshared key (all other settings are set to defaults). Router is configured to use transport mode, l2tp, 3DES, MD5, DH group 2, and a preshared key. But when they try to establish the same VPN-connection on Vista they most often get error 789 (negotiation failed). May be there is some new policy or enabled option which affects ISAKMP in Windows Vista?
I have this problem too.