FortiGate 2GB Memory Models Are Slowly Reaching Their Performance Limits

As a FortiGate support provider, we occasionally identify concerning trends in support requests that we believe are crucial to share with the community. Lately, we have seen a significant increase in 2GB memory FortiGate models hitting their performance ceilings. While these legacy platforms have proven themselves over the years – and many have already been replaced – we want to raise awareness for organizations still relying on this hardware.

Since the initial release of the 2GB models, the networking and security landscape has evolved drastically. Numerous FortiOS updates have introduced resource-intensive features that are being deployed more frequently (e.g., IPv6, IKEv2, ZTNA, SD-WAN, Dynamic Routing and many more). Naturally, these features demand more processing power and generate a higher system load.

Fortinet has also implemented various OS-level security measures that unfortunately come with a performance cost. Furthermore, external factors outside of FortiOS contribute heavily to this load: stronger encryption standards, heavier overall traffic, more complex hashing algorithms, the global shift toward encrypted connections, and exponentially growing FortiGuard databases (including more applications, Internet Services, geographical objects, antivirus signatures, and so on…).

The Threat of Conserve Mode

Due to this increased load, many FortiGates enter Conserve Mode when memory usage spikes too high. You can check if your FortiGate has entered Conserve Mode by running this CLI command:

diag deb crashlog read | grep mode

As an initial mitigation step in newer firmware versions, Fortinet’s 2GB memory models no longer support SSL VPN, proxy-based inspection, or IoT/OT signatures. Disabling these resource-heavy applications saves a significant amount of memory.

Fortinet provides a technical tip to help defuse the situation, but ultimately, configuration optimizations cannot physically extend the memory and will not permanently solve the root problem: https://community.fortinet.com/fortigate-3/technical-tip-how-to-optimize-memory-consumption-for-smaller-fortigates-94683

It is also worth noting that Fortinet mentions 4GB memory models as potentially affected in this article. Therefore, upgrading to a 4GB model might just postpone the issue for highly demanding environments rather than solving it permanently. For further reading, see this general guide: https://community.fortinet.com/fortigate-3/technical-tip-free-up-memory-to-avoid-conserve-mode-126682

FortiGate 2GB Memory Models: Hardware Limitations

The RAM in FortiGate hardware appliances is directly soldered onto the circuit board or integrated into the SoC chipset (SoC3 = 2GB RAM; SoC4 and SP5 are available in both 2GB and 4GB versions). Because of this integrated architecture, it is impossible to physically upgrade the memory of a hardware FortiGate. (Note: In FortiGate virtual machines, memory can easily be expanded depending on your licensed resources).

Find out how much RAM your FortiGate has

You can verify your built-in memory using these CLI commands:

get hardware memory
get system performance status

List of 2GB Memory FortiGate Devices

In general, those are the FortiGate 2GB Memory Models in the F und G series:

F-Series:
FortiGate/FortiWiFi 40/41F
FortiGate/FortiWiFi 40F-3G4G
FortiGate/FortiWiFi 60/61F
FortiGate Rugged 60F (not all variants!)

G-Series:
FortiGate/FortiWiFi 30/31G
FortiGate/FortiWiFi 50/51G
FortiGate/FortiWiFi 50G-DSL
FortiGate/FortiWiFi 50/51G-5G
FortiGate/FortiWiFi 50G-5G-II
FortiGate/FortiWiFi 50G-SFP
FortiGate 50/51G-SFP-POE

The Solution: Trade-Up Your FortiGate

All FortiGate models with 2GB of memory have been added to the Trade-Up list and can therefore be exchanged for discounted new hardware.

Requirements for a Trade-Up:

• Active FortiCare Services.
• The device must be on the official Trade-Up list.
• Only specific upgrade paths are permitted.

Trade-Up Matrix:

Note: Since Trade-Up offers are generally reserved for older hardware models in a phase-out status, the G-Series models are not yet on this list.

Please feel free to contact our sales department for a non-binding Trade-Up offer. Don’t forget to include the serial number(s) of your old FortiGates in your message so we can calculate your upgrade options accurately.

Automation Stitch for Conserve Mode

By default, the FortiGate does not actively notify administrators about Conserve Mode events. We highly recommend creating an Automation Stitch to trigger an email alert when memory runs critically low:

# 1. Trigger
config system automation-trigger
    edit "Trigger-Conserve-Mode"
        set trigger-type event-based
        set event-type low-memory
    next
end

# 2. Action
config system automation-action
    edit "Action-Email-Admin"
        set action-type email
        set email-to "recipient@yourdomain.com"
        set email-subject "%%log.hostname%%: Conserve Mode Alert"
        set message "FortiGate %%log.hostname%% has entered Conserve Mode!"
    next
end

# 3. Automation Stitch
config system automation-stitch
    edit "Stitch-Conserve-Mode"
        set trigger "Trigger-Conserve-Mode"
        config actions
            edit 1
                set action "Action-Email-Admin"
                set required enable
            next
        end
        set status enable
    next
end

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