Remove your 3G/4G USB dongle from the router port before beginning the update.
Visit the official Tenda Download Center and search for "4G630" to download the latest available firmware for your specific hardware version. tenda 4g630 firmware update
A file explorer window will open. Navigate to the folder where you extracted the downloaded firmware. Select the file ending in .bin and click . Remove your 3G/4G USB dongle from the router