Technical Tip: FortiGate with 5G modem not coming up after upgrading to FortiOS v7.4.11

Description

This article describes an under investigation issue where FortiGate with 5G modem may not connect to the provider tower after upgrading to FortiOS v7.4.10 or later.

Scope

FortiGate platforms with integrated 5G modem, such as FGT_50G_5G/FWF_50G_5G/FGR_50G_5G.

Solution

After upgrading to FortiOS v7.4.11, the FortiGate's 5G modem may fail to connect to the carrier network. The issue is site-specific and not isolated to a particular carrier.

Workaround:

If the device was upgraded from a previous firmware version, it is recommended to revert to the previous firmware image using the alternate partition, rather than perform a downgrade, see Technical Tip: Selecting an alternate firmware for the next reboot.

Alternatively, configure the modem to 4G-only mode:

config system 5g-modem
    config modem1
        set network-type 4g
    end
end

If it is not possible to revert the FortiGate to a previous firmware version or change the network-type, see Technical Tip: Formatting and loading FortiGate firmware image using TFTP and Technical Tip: FortiGate Firmware Downgrade for Minor Releases.

Resolution:

The issue is scheduled for fix in upcoming FortiOS releases v7.4.12, v7.6.7, and v8.0.0, see issue ID #1263001 in FortiOS Release Notes.

If the FortiGate does connect to Verizon network but reconnects every few minutes, see Troubleshooting Tip: FortiGate with 5G modem flapping when connecting to Verizon carrier using Static SIM Card.