Flashing firmware on a display module is not like updating a smartphone. You need a dedicated programmer (ESP32, STM32, or USB-to-SPI adapter). If you brick the display, you may need to re-flash via the ISP header.
If your device is still running older software, you can manually check for the latest version: Resource Center - DrayTek
: Use the admin username and password located on the sticker at the back of your device. Find the Version : Navigate to the System Information
Which would you prefer?