Sites like ADSLZone or OpenWrt (if you are looking for custom firmware) sometimes host mirror links, though you should exercise caution with .rar files from unofficial sources. Important Precautions
The safest bet is the Kasda Support Page. Look for the "Download" or "Firmware" section and search for . Download KASDA KW5515 Firmware rar
Never update firmware over Wi-Fi. Use an Ethernet cable to prevent the connection from dropping during the update. Sites like ADSLZone or OpenWrt (if you are
Always scan .rar files for malware before extracting them. Never update firmware over Wi-Fi
Ensure the firmware version matches your hardware revision (usually found on a sticker at the bottom of the router). Flashing the wrong version can "brick" the device.
If your router was provided by an internet service provider (ISP), they often manage the firmware updates. Check your ISP's support site for device-specific downloads.