For technical users, the D-Link FTP Repository contains archived firmware versions categorized by hardware revision (H/W Ver.).
Once you have the correct .bin or .img file, follow these steps to update: Index of /pub/ADSL/DSL-2740U/Firmware - D-Link FTP
Look at the label on the bottom of your router. Look for the string "H/W Ver." (e.g., A1, V1, V2, or C5).
Installing the wrong firmware can permanently "brick" your router. Before downloading, verify your specific hardware version:
General D-Link firmware sets can occasionally be found on the Official D-Link Firmware SourceForge . Critical Pre-Installation Checks
This firmware is only compatible with hardware revision С5. Please take a look at string "H/W Ver." on the sticker of your device. D-Link FTP Wireless N300 ADSL2+ Wi-Fi Router DSL-2740U - D-Link
Downloading and installing the official is essential for maintaining the security, stability, and performance of your D-Link router . This specific firmware update is designed to fix bugs and improve the hardware's interaction with modern ADSL2+ standards. Official Download Sources