With IPHost Network Monitor you can run simple snmp requests against a Fortinet device in your network.
fgVpnSslState
fg Vpn Ssl State
1.3.6.1.4.1.12356.101.12.2.3.1.1
Whether SSL-VPN is enabled on this virtual domain
Back to FORTINET-FORTIGATE-MIB MIB page.
IPHost Network monitor allows you to monitor fgVpnSslState on Fortinet device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Fortinet WAN extenders right now.