Action required: Apply the fix for SNS firewall disks.
Please follow the procedure described in the How to update my SSD Firmware - Stormshield Knowledge Base article (authentication required).
Cabling SNS firewalls and booting on a USB drive
On some SNS firewalls, the usual boot sequence must be interrupted in order to boot on a USB drive. Cable connections and the boot configuration vary by model.
Continue according to the model of your SNS firewall: