To help find the exact update you need, let me know your current and your Internet Service Provider (ISP) so I can pinpoint the best specific software build for your network. Share public link
If the router rejects the file, you likely downloaded the wrong version. dsl3890 firmware link
Whether you are using it for a home office, streaming, or general browsing, a glitchy connection can bring your digital life to a halt. When bugs surface or security vulnerabilities are found, the only real solution is a firmware update. To help find the exact update you need,
You can find the official firmware, manuals, and setup guides on the D-Link Support Resources for DSL-3890 . Direct download folder for REV A . or general browsing