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Wireless Reviews

Wireless Performance Overview

The DIR-857 is Wi-Fi Certified and both bands defaulted to Auto 20/40 Channel Width upon power-up. Since this is the new normal for 802.11n products I ran two new tests to see if the 857 properly refrained from switching into 40 MHz bandwidth mode. I'm happy to report that, like the DIR-827, both the 40 MHz Coexistence and Fat channel intolerant tests passed. So you don't have to worry about the DIR-857 stepping on neighboring WLANs, even when it is set to Auto 20/40 mode.

I successfully ran a Wi-Fi Protected Setup (WPS) session with a Win 7 client by entering the WPS code found on the router's bottom label. The WPS session completed quickly and resulted in a WPA2/AES secured connection with the same WPA2 pre-shared key set for both radios. All tests were run with this secured connection using our current wireless test process.

The router comes with dlink set for the 2.4 GHz SSID and dlink_media for 5 GHz. But it is important to note that when I entered a network name (SSID) as prompted by the Windows WPS wizard, both radios were set to the same SSID! This isn't much help if you have dual-band clients, so you'll have to go back and manually set each radio to a unique SSID so that you can select the band you connect to.

As with all "N-900" routers, we'll start with an overview, then provide the details for those who want to dig into the details.

The Benchmark Summary below shows once again that the overall average difference between two and three stream operation isn't that striking, except for the "up/down" tests that run two traffic streams simultaneously.

DIR-857 benchmark summary
DIR-857 benchmark summary

Table 4 summarizes the highest wireless throughput measured out of all locations in the 20 MHz mode test runs. In all cases, the highest throughput was measured in Location A.

Test Group Max Dn (Mbps) Max Up (Mbps) Dn/Up (Mbps)
2.4 GHz, 2 stream, 20 MHz 63 55 81
2.4 GHz, 3 stream, 20 MHz 83 60 104
5 GHz, 2 stream, 20 MHz 65 57 82
5 GHz, 3 stream, 20 MHz 66 70 96
Table 4: Highest Throughput, 20 MHz mode

These results are unimpressive. The highest-performing N routers produce around 80 Mbps best-case throughput in 20 MHz mode as you can see on this maximum throughput chart. The DIR-857, in contrast, only manages 62 Mbps downlink and 55 Mbps up. Simultaneous up/down performance ranks a bit better, measuring 81 Mbps vs. a best case of 94 Mbps.

Perusing Tables 4 and 5 or stepping through the wireless throughput benchmarks with the mode selector set to Maximum tell a similar story. In case after case, the 857 ranks mid-chart or lower vs. other two and three-stream N routers for its two-stream performance. And while there are exceptions, maximum throughput generally doesn't change much between two and three-stream measurements, except when multiple simultaneous test streams are used.

Test Group Max Dn (Mbps) Max Up (Mbps) Dn/Up (Mbps)
2.4 GHz, 2 stream, 40 MHz 68 70 97
2.4 GHz, 3 stream, 40 MHz 92 76 128
5 GHz, 2 stream, 40 MHz 69 66 98
5 GHz, 3 stream, 40 MHz 78 79 109
Table 5: Highest Throughput, 40 MHz mode

The DIR-857's story is a bit brighter for three-stream benchmarks. There are a few cases where it ranks near the top of the chart, and one 5 GHz benchmark, where it actually comes out on top.

The overall takeaway, however, is that the DIR-857 is not going to be the router you'll choose if you're looking for best wireless performance.

Wireless Performance - 2.4 GHz Two Stream

For performance comparison, I chose two other full "N-900" routers: the ASUS RT-N66U "Dark Knight" and Cisco Linksys E4200V2. And since so many people seem interested in seeing whether draft 11ac routers can out-perform the current crop of 802.11n routers, I threw in Buffalo's WZR-D1800H into the mix.

The comparison tables are large, so I have provided links that will open each one in a new window/tab to make things easier. Let's start with the Performance Table for 2.4 GHz, 2 streams. The Dark Knight is the clear winner in this round, taking three out of four comparisons. But the Buffalo draft 11ac router takes the 20 MHz mode uplink benchmark, primarily due to better throughput in the medium-low and low signal level test locations D and F.

The IxChariot plot summary below for 20 MHz mode downlink shows generally stable throughput, with some moderately long dropouts in the weakest signal location F. You will see this also in the 20 MHz mode uplink plot linked below.

D-Link DIR-857 IxChariot plot summary - 2.4 GHz, 20 MHz mode, downlink, 2 stream
D-Link DIR-857 IxChariot plot summary - 2.4 GHz, 20 MHz mode, downlink, 2 stream

Here are links to the other plots for your reference.

More Wireless

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