If you must update, obtain the exact firmware from your ISP's maintenance window release notes. Use a serial console to monitor the boot process and ensure JTAG recovery pins are accessible before starting.
ISP-locked units (e.g., Telmex, Claro, China Unicom) often reject generic firmware. You may need a “universal” or “unlocked” version. Always check your current firmware via the web UI: Status > Device Info .
Browser cache or old config corruption. Fix: Clear browser cache. Perform a hardware reset (30-30-30 method: hold reset for 30 seconds while powered, unplug power while holding for 30 seconds, plug back in while still holding for 30 seconds – rare but effective).
