More VPN issues to report.

We have a husband and wife team at my place of work, both have company laptops. Carl uses Fortinet VPN client to access our main network remotely and it works fine. Natalie uses netscreen remote to access our support network, well actually she doesn't because it just will not work. I have tested the PC from one Lan to the other and it works nicely. Don't really want to make a home visit.

I was planning to change ISP to Sky but have to be able to access both of the above networks.

Any ideas why Fortinet would work and Netscreen not?