Index of /pub/ADSL/DSL-2750U/Firmware. This firmware is only compatible with hardware revision С. Please take a look at string "H/ D-Link FTP How to update your D-link router (DSL 2750) - step by step
To ensure you have the correct version for your hardware revision (which is critical to avoid bricking the device), use these official regional sources: D-link Dsl-2750u V2 Firmware Me-1.30 Download