FortiClient "VPN Connection Failure" - cannot log in from laptop

[JJirsa]

First off, I only have access to the client side of FortiClient.  The company who set up the VPN have been of little help, partly because the guy who actually configured the VPN recently quit and no one is familiar with what he did.  In the past I was able to log in on my laptop from home, but now I get the following error:

"VPN Connection failed.  Please check your configuration, network, connection and pre-shared key then retry your connection.  If the problem persists, contact your network administrator for help."

Important info that makes me think it is NOT my credentials (username/password):

1. If I try to connect while my laptop is on our whitelisted office network, I successfully log in.

2. If I try a different person's credentials from my laptop, I still get the error even though they can log in from their own laptop.

3. Out of 6 people in my office using the VPN, I'm the only one with this issue.

Could there be some process or app running on my laptop that is creating a conflict with FortiClient?  I admit I know little about VPN clients, other than they usually just work.  I'm running Windows 7 on a Lenovo ThinkPad, standard McAfee virus scan installed by company IT group.  Not sure what other info might help ID the issue, but I'm travelling and really need to get this worked out.  Thanks in advance.

[ede_pfau]

This is not an easy one. Partly because the people in charge are of no help - this is a no-go. For them, it should be a matter of minutes to help you get going.

Secondly, there aren't that many parameters which need to fit for a SSLVPN connection, besides name and password.

It could be that your client is trying to contact the gateway on a wrong port. You would easily find this when you compare your client configuration with someone else's. The port is / may be specified in the address field of the gateway: "Remote Gateway", "Use Port" (or the like) checked and port number specified (in the range of 443 to 65535). If no deviant port is specified, port 443 is used.

Then there is a checkbox for "Use client certificate" which usually is not enabled. Again, compare to other, working client.