This is a part of my personal notes. Use this information at your own risk. If you are uncertain or don’t know what you are doing. Do not proceed.
Asus RT-N66U is a Linux based wireless router. The stock firmware can be a bit limiting for the more advanced user. If you want better QoS, OpenVPN or just more control over the network I recommend installing Tomato by Shibby firmware.
Download the latest version of the firmware from Tomato by Shibby. Look for Asus RT-N66u 64k in the version folder in K26RT-N repository.