A catastrophic bug caused the router to reboot every 30–90 minutes without logging a kernel panic. ISPs pulled this version within 48 hours, but many routers received it.

Do NOT trust third-party websites claiming to host “Fast 4315 factory firmware.” Those are often malware or incomplete dumps. Your ISP is the sole source.

Ensure you haven't unzipped the .bin file. The router needs the raw file. Also, verify that the firmware matches your specific hardware revision.

✅ Good if your ISP keeps it current (within 6–12 months). ❌ Frustrating if you’re stuck on a two-year-old build with known issues.

This is the most critical concept to understand regarding this device.