The initial 5 dB step 3.354 run comes in highest, the 3 dB step 3.354 retest in the middle and the new 4.372 firmware the lowest. ASUS RT-AC66U 2.4 GHz Downlink Throughput vs. Attenuation. Differences in 2.4 GHz uplink performance are much harder to parse.
What is Tomato? Tomato is a small, lean, open source alternative firmware for Broadcom-based routers. It features a new user-friendly GUI, a new bandwidth usage monitor, more advanced QOS and access restrictions, new wireless features such as WDS and wireless client modes, a higher P2P maximum connections limit, the ability to run custom scripts, connect via telnet/ssh, reprogram the SES/AOSS RT-AC66U - dlcdnets.asus.com RT-AC66U Dual Band 3x3 802.11AC Gigabit Router The ultra-thin and stylish RT-AC66U features a 2.4GHz and 5GHz dual bands for an unmatched concurrent wireless HD streaming; SMB server, UPnP AV server, and FTP server for 24/7 file sharing; a capability to handle 300,000 sessions; and the ASUS Green Network Technology, which provides up to 70% power- About | Asuswrt-Merlin Jun 28, 2020 Asuswrt-Merlin download | SourceForge.net
RT-AC66R | Networking | ASUS USA
Download | Asuswrt-Merlin Jun 28, 2020 Download Asus RT-AC66U Drive Software, & Wireless Setup Jul 07, 2019
Boosting performance of Asus RT-N66U - Gunnar Peipman
Latest AdvancedTomato firmware releases and downloads for Asus RT-AC66U