The safest way to acquire firmware is directly from the source. You can access the Official Sagemcom Support Website to search for your specific device category—such as Gateways (DSL, Cable, Fiber), Set Top Boxes, or Smart Meters.
Sagemcom has a public support portal for non-ISP locked devices (e.g., retail versions of the Fast 5364 or Twingy). Here is the direct path: Sagemcom Firmware Free Downloads
: ISPs use "Remote Management" (TR-069 protocol). The safest way to acquire firmware is directly
Here are legitimate starting points (copy and paste into your browser): Set Top Boxes