Some of our users need to use the Cisco Anyconnect SSL VPN Client to connect to network of a business partner. This works without problems on most of the machines, however on some machines, the client is not able to connect to the VPN.
On those machines, user get two error messages saying "The VPN client is unable to establish a connection" and "Unable to establish VPN".
All Clients run Windows Vista Enterprise (x86 and x64) and use Cisco Anyconnect VPNClient Version 2.4.0202.
According to the logs on the client machines, i think that there is a problem regarding the source ip address, the client is using to connect to the VPN Server (because this is something that differs between the logs of a working and the logs of a not-working client)
If the client is able to connect, the eventlog entry looks like this:
Opened SSL socket from 172.16.0.121 to [Server IP]
If the client is not able to connect, the eventlog entry looks like this:
Opened SSL socket from 127.0.0.1 to [Server IP]
Could the use of the loopback address be the problem or has someone experienced something similar?
I can rule-out local and perimeter firewalls and any other network security device that is in use. In addition, the clients are deployed with a standardized image, so there is no difference regarding installed software.
Thanks for any help!