I used the open air test method described here to test the 400N's wireless performance. Testing was done using the new SNB standard wireless test client, an Intel Wi-Fi Link 5300 AGN mini-PCIe card and 184.108.40.206 driver in a Dell Mini 12 running WinXP Home SP3. I left all client-side defaults in place except for enabling throughput enhancement (packet bursting).
The router had the latest 1.0.01 B19 firmware and I left all factory default settings in place, except to set channel 1 for the 2.4 GHz mode tests and channel 36 for the 5 GHz tests.
Figure 6 shows a composite of downlink throughput tests made at the six test locations in four wireless modes: 2.4 GHz, 20 MHz channel; 2.4 GHz, 40 MHz channel; 5 GHz, 20 MHz channel; and 5 GHz, 40 MHz channel. Each column represents the average throughput from a one minute test. Best case downlink throughput of 65.7 Mbps was measured using a 40 MHz channel in the 5 GHz band.
Figure 6: WRT400N six location downlink summary
As usual, I wasn't able to connect to the 400N in Locations E and F in 5 GHz using either a 20 or 40 MHz channel. But speeds on the 2.4 GHz band were actually pretty good in Location E and usable in Location F.
Figure 7 shows a composite of the actual IxChariot test results running downlink 2.4 GHz w/ 20 MHz channel. Throughput variation is better than most other draft 11n products that I have seen and much better than the WRT610N's (see the plot). I can't say for sure why the variation is lower since I used different test clients.
Figure 7: Six location wireless throughput - 2.4 GHz, 20 MHz channel, downlink
Figure 8 shows the six location plot for the uplink direction. Best case uplink throughput of 68.4 Mbps was measured using a 40 MHz channel in the 5 GHz band at Location A. Up and downlink speeds were generally evenly matched, except for a big difference in Location A, 2.4 GHz, 40 MHz mode. (See Figure 6 for the table of throughput values.)
Figure 8: WRT400N six location uplink summary
The IxChariot uplink plot looks very similar to the downlink. You can see it here if you want.