Before downloading any files or modifying your router settings, you must take a few precautionary steps to prevent bricking your device (making it permanently unusable).
Download the correct file. Ensure you have the exact firmware for the ND300V2 model. Using software meant for a different version can permanently damage the device. Update Software in TOTOLINK ND300V2
Once the upgrade begins, the router’s flash memory is wiped and rewritten. During these 2–5 minutes, the power supply must remain uninterrupted. Once complete, the device will automatically reboot. Post-Update Integrity Before downloading any files or modifying your router
For the ND300V2, TOTOLINK supports the "TOTOLINK Manager" or "TOTOLINK WiFi" app (depending on your region). Update Software in TOTOLINK ND300V2