Look at the sticker underneath your router. It must say H/W Ver: C1 . Installing firmware for a different revision (like T1 or V1) can permanently damage (brick) the router.
Never flash firmware intended for version T1, U1, or any other revision onto a C1 device. Doing so can render your router permanently unusable (a "brick"). d-link dsl-2750u c1 firmware
Versions such as 1.0.14 are often used to enable advanced features like MAC cloning. Look at the sticker underneath your router
If the emergency web server fails, you need a USB-to-TTL adapter (3.3V). Solder/solderless connect to the board's RX, TX, GND pins (usually near the CPU). Use PuTTY to interrupt the boot process and flash via tftp . Never flash firmware intended for version T1, U1,
For the DSL-2750U C1, firmware updates have been sparse. D-Link typically releases these updates through regional ISP partners rather than a centralized global download page. Consequently, many users find themselves running outdated firmware years after purchase.