I acquired a DIR-825 B-revision just recently. It has DD-WRT installed, however I would like to put OpenWRT on it. The procedure, as per the DD-WRT documentation seems to be to first flash the factory image (which is, luckily, downloadable from the D-Link website), and then flash OpenWrt install image via the recovery.
However, there doesn't seem to be an OpenWrt install image available for this particular device. The link at the device page points to 19.07.4 squashfs-factory image of the target ar71xx-generic, which isn't available. How would go about obtaining the squashfs-factory image of the target ath79-generic for this particular device?