I just want to follow up and clarify the problem I was having. I am not talking about using the ssl-vpn client or even doing anything ssl-vpn related other than connecting to the ssl-vpn portal site to just get to the login screen.
My users would not even be able to get to the login screen of the ssl-vpn portal, it would work then randomly it would stop working (site would time out). The only two ways to fix it was to restart the device (which was not good in the middle of the way) or to change the ssl-cert to a different one, apply changes, browser to the portal page, then go back to the admin and change it back to your original ssl-cert.
Oh and I did verify it also happened to the self-signed Fortinet ssl-cert, so it doesn' t matter if you are using your company' s ssl-cert or Fortinets.
Anyway ever since I updated the firmware this problem has not occurred.
Luis