Use an Ethernet cable to connect your computer to the router. Updating over Wi-Fi is risky as a connection drop can "brick" the device. Stable Power:
and search for "ND300". Download the firmware version that matches your hardware (V2). Update Software in TOTOLINK ND300V2
TOTOLINK ND300V2 Firmware Version: V3.0.0c_B20190213 Use an Ethernet cable to connect your computer to the router