Ensure your computer is connected to the Tenda D305 via an Ethernet cable . Using a Wi-Fi connection for updates is risky as an interruption can "brick" the device.
Download firmware only from Tenda’s official support site: https://www.tenda.cn or your regional Tenda site (for example, https://www.tenda.com.cn or https://www.tendacn.com). Search there for "D305" and select the correct hardware version. tenda d305 firmware update link
Stay tuned for more tech-related blog posts and guides! Ensure your computer is connected to the Tenda
*If you experience difficulties finding the specific file for your region, contacting Tenda Support via their official website is tenda d305 firmware update link