A: Yes, underscore or hyphen – it’s the same release.

: Click Browse to select the unzipped .bin file you downloaded.

Official sources are now scarce because D-Link removed most legacy firmware from its global support portals after 2020. However, you can still obtain the verified file from:

: A firmware update may reset your router to factory defaults. Ensure you have your ISP credentials (PPPoE username/password) written down before starting. How to Install Index of /pub/ADSL/DSL-2750U/Firmware - D-Link FTP