The ASUS RT-AC56U is Wi-Fi certified. It defaulted to Auto channel mode on both 2.4 and 5 GHz radios upon power-up. The 2.4 GHz radio defaulted to Auto 20/40 MHz Channel width, while the 5 GHz radio defaulted to 80 MHz. The router comes with different 2.4 and 5 GHz SSIDs set, so you'll be able to connect to your desired band without having to change router settings.
In the WPS test, the Windows 7 client prompted for and completed pushbutton session on 2.4 GHz radio. It did not prompt on 5 GHz radio. This appears to be due to router setting. It looks like WPS can only be used on one band at a time.
Being Wi-Fi certified, it's no surprise that the RT-AC56U passed both the Fat Channel Intolerant test as well as the 40 MHz coexistence test. For the Fat Channel test, the router switched to 20 MHz link rate immediately when bit was enabled but stayed at 20 MHz link rates when bit was disabled.
For the 40 MHz coexistence test, it switched immediately to 20 MHz link rates when set to Channel 8 and back to 40 MHz mode when moved back to Channel 6. (The "neighboring" network for these tests is on Channel 11.)
For throughput testing, all tests were run using our standard wireless test process and 22.214.171.124.374.134 version firmware loaded. The router was first reset to factory defaults and Channel 6 was set for 2.4 GHz and Channel 153 for 5 GHz. 20 MHz B/W mode was set for 2.4 GHz and 5 GHz was set in 80 MHz bandwidth mode. The closest surface of the router was positioned 8" from the chamber antennas in 0° and 180° test positions. The 0° position had the front of the router facing the chamber antennas.
The Benchmark Summary below shows the average of throughput measurements made in all test locations.
ASUS RT-AC56U Benchmark Summary
To date, we have tested seven AC1200 class routers. As of this review, the AC56U ranked #1 in three of the four benchmarks included in the Average Wireless Throughput ranking. For the 2.4 GHz average uplink test it came in #2, bested only by one of the three routers tied for fifth place. The NETGEAR R6100 turned in 66.6 Mbps compared to the ASUS's 63.4 Mbps.
For Maximum Wireless Throughput, again the RT-AC56U ranked #1 in three out of the four tests. And, like the average wireless throughput tests, the 2.4GHz uplink was the only score that wasn't a first place finish.
The Throughput vs. Attenuation plots give you a better idea about how the router is going to perform throughout its entire range. Tests are run with 3dB of attenuation added for each data point. More attenuation simulates more distance from the router. Routers performing well with higher attenuation are more likely to provide you with better coverage for your environment.
For these tests, I decided that it would be interesting to compare the RT-AC56U with the other two top-ranking AC1200 class routers - Edimax's BR-6478AC (#2) and D-Link's DIR-860L (#3). As you'll see in the charts below, the RT-AC56U really did earn its #1 ranking.
For the 2.4 GHz downlink test, notice how the line for the RT-AC56U stays consistently above the compared products and, on the down slope of the curve, to the right of them. On the down slope of the curve, the Edimax gave the RT-AC56U a good run for its money and matched the slope of the curve. But the gap between the curves showed that the RT-AC56U still had a significant performance advantage - between 14 Mbps and 18 Mbps between 36 dB and 54 dB of attenuation.
2.4 GHz Downlink Throughput vs. Attenuation
The 2.4 GHz uplink tests showed that the Edimax's performance tracked the ASUS's performance throughout the entire range. On the last test at 63dB of attenuation, the Edimax held the connection but the ASUS dropped it. At 60 dB, both had the same 9 Mbps of throughput. Beyond 15 dB of attenuation, the DIR-860L dropped below and to the left of the other two routers and came in a distant third.