As of recent records, versions such as 4.0.1 and 4.5.1 (specifically for the R3/A3 hardware) are available.
the correct firmware file (usually a .bin file) from the links above.
The most reliable source for the hardware revision is the Eastern European/Russian support repository, which lists multiple versions for the (A3 equivalent):
The DIR-853 is a popular wireless router model from D-Link, known for its reliable performance and robust features. Similarly, the A3 is another notable device that requires periodic firmware updates to ensure optimal functionality, security, and compatibility. In this write-up, we'll explore the importance of firmware updates for DIR-853 and A3, and provide a direct link for updating the firmware.
Before downloading any files, confirm that you have the hardware revision. Installing firmware meant for a different revision (like A1 or A2) can permanently damage (brick) your router.
⚠️ : Do not download firmware from third-party forums or unverified links. Only use official D-Link domains.