Some sites compile links for various DVRs based on the hardware version (e.g., V4.02.R11), which can be helpful if your device is unbranded but uses Dahua-compatible hardware. Updating the Firmware
Do you have the from the sticker or the system menu to help narrow down the exact file? Firmware Update via USB Drive - Dahua Wiki
Installing the wrong firmware can "brick" your device, making it unusable.
Finding the right firmware for a Dahua 8-channel DVR often involves matching the specific model number to official files found on the DahuaWiki Firmware page .
Check the sticker on the bottom of the device or the System Info > Version menu in your DVR settings.
Go to the DahuaWiki and use their Firmware Tool to type in your model number and get a direct download link.
A "16MB" firmware file typically refers to the size of the flash memory on the DVR's motherboard, a common spec for many 8-channel units using HiSilicon SoCs. How to Find Your Firmware