The only hardware difference is internal storage. The 91G ships with a 120 GB SSD for local logging, WAN optimization, and FortiGuard database caching. The 90G has the same ports, FortiSP5 ASIC, and performance numbers but no onboard storage. Both models accept the same FortiGuard service bundles and FortiCare support tiers, so the licensing and subscription paths are identical.

Fortinet rates the 90G series for environments with 200 to 500 users. Actual headroom depends heavily on which security services you run. Full threat protection with SSL inspection draws more resources than a basic firewall policy. Our engineers can help you size the right model against your actual traffic mix, concurrent session count, and service requirements before you order.

Fortinet offers three main service tiers for the 90G and 91G. Advanced Threat Protection covers IPS, malware protection, and application control. Unified Threat Protection adds URL filtering, DNS security, and antispam on top of that. The Enterprise Protection bundle is the most complete, adding inline CASB, DLP, AI-powered inline sandbox, attack surface monitoring, and the FortiConverter migration service. All tiers are available in one-, three-, and five-year terms bundled with FortiCare Premium support.

Yes. SD-WAN is built into FortiOS and runs on the FortiSP5 ASIC alongside the firewall engine, so there is no separate license fee and no extra appliance. The 90G supports application-aware traffic steering, WAN path monitoring, dynamic path selection, and automatic uplink failover. It is the same SD-WAN stack that earns Fortinet its Gartner Magic Quadrant Leader position, running on a desktop appliance priced for branch and mid-market deployments.

The 90G supports Active-Active, Active-Passive, and clustering HA. A dedicated front-panel HA port connects directly to a paired unit. For distributed sites where a redundant pair is not practical, the 90G also works with FortiManager zero-touch provisioning, so a replacement unit can pull its full configuration automatically without requiring on-site IT staff to intervene.