Whether you are flashing stock recovery or OpenWrt, follow this ritual for the C1:
Important: The C1 has a small flash memory (8MB). If you try to install a full OpenWrt build with a GUI (LuCI), you will run out of space. Use the mini build or the command-line interface. d-link dsl-2750u c1 firmware
Visit the official D-Link support site for your region. Ensure the filename you download explicitly mentions C1. Whether you are flashing stock recovery or OpenWrt,
Pro Tip: If you cannot find the file on the main website, try the D-Link ftp server or regional sites (like D-Link India, Middle East, or Russia), as this model was very popular in those markets. Important: The C1 has a small flash memory (8MB)
Even with updated firmware, the DSL-2750U C1 can show its age. Here are fixes for the most common problems: