Since your request is a bit broad, I’ve drafted three versions of a "proper post" depending on where you plan to share it.
Historically, D-Link kept firmware on ftp.dlink.de or ftp.dlink.com . However, many old links are dead. As of 2025, the recommended approach is using the with your product’s hardware revision (look on the sticker under the device: H/W Ver: A1, A2, B1, etc.). dlink dsl224 firmware