With IPHost Network Monitor you can run simple snmp requests against a Fortinet device in your network.
fgIpSessExp
fg Ip Sess Exp
1.3.6.1.4.1.12356.101.11.2.1.1.7
Number of seconds remaining before the session expires (if idle)
Back to FORTINET-FORTIGATE-MIB MIB page.
IPHost Network monitor allows you to monitor fgIpSessExp 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.