Forticlient SSL VPN intermittent connection issues over Verizon Jetpack

[AkamaiBrian]

Hello,

I have a client running Forticlient SSL VPN over Verizon Jetpacks.  We have seen intermittent connection issues with multiple users, multiple laptops and Jetpacks in different locations.  The problem is the initial connection of the VPN.  Sometimes it works, and then literally 2 minutes later it will fail (and vice versa).  Out of 20 connection attempts, it failed on 12 and was successful on 8.  Over the hour that I was investigating the issues, I was connected to the laptop via splashtop remote desktop and never once lost a connection.  A continuous ping to 8.8.8.8 never dropped a packet.  That being the case, I do not believe that the Cellular hotspot was in any way responsible.  I verifies that VPN passthrough was enabled on the jetpack.  Additionally, from a wired internet connection from the same machine, the connection attempts were 100 % successful. I am using the Static IP of the Fortigate 50E firewall in the connection setting in order to rule out DNS.  I can browse to the Web Portal on the firewall, so the routing is working. I'm pulling my hair out trying to figure out what is going on here.  Thank you in advance for your assistance.

[patelr]

Hello @AkamaiBrian,

Please share FortiGate OS and FortiClient OS. 

Have you tried enabling DTLS on FortiClient, enabling preserve-session-route on public facing interface as issue might occur if there are multiple interfaces connected to the Internet, for example, SD-WAN, and this can cause the session to become 'dirty'.

Please provide any logs collected on FortiGate, and on FortiClient, and review https://community.fortinet.com/t5/FortiGate/Technical-Tip-SSL-VPN-disconnection-issues-when-connecte...

Thanks,
Ronak Patel