Mobile network operators frequently tweak their cell towers (upgrade to 4.9G, change frequency bands, or adjust handover parameters). Outdated firmware on your 5366 can lead to dropped connections, slower speeds, or failure to connect to new towers.

Some ISPs host firmware on public FTP servers. For example, older Ziggy builds are at ftp.ziggo.nl/firmware/sagemcom/ . However, always verify checksums.

Most Sagemcom routers are configured to auto-update. The router checks for new firmware nightly. If an update is available, it downloads and installs between 2:00 AM and 4:00 AM. You can force an OTA check: