With IPHost Network Monitor you can run simple snmp requests against a Fortinet device in your network.
fgHaStatsNetUsage
fg Ha Stats Net Usage
1.3.6.1.4.1.12356.101.13.2.1.1.5
Network bandwidth usage of specified cluster member (kbps)
Back to FORTINET-FORTIGATE-MIB MIB page.
IPHost Network monitor allows you to monitor fgHaStatsNetUsage 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.