The DIR-685 is an interesting "all-in-one" router incorporating a 2.4 GHz draft 802.11n access point, four-port Gigabit Ethernet switch and WAN port, 3.2" color LCD screen and built-in NAS (when you add a 2.5" SATA hard drive, 1 TB max.).
The NAS includes UPnP AV / DLNA and iTunes media servers and BitTorrent download client. The LCD screen can display photos stored on the hard drive or online photos and content via D-Link's FrameChannel partner service in addition to status information. Read and write throughput measured via a Vista SP1 file copy measured around 5 MB/s for write and 11 MB/s read from a Gigabit-connected client.
The DIR-685 has 64 MB of RAM and 32 MB of flash and a 2x2 draft 802.11n radio based on a Ralink RT2880F 2T3R MAC/BB and RT2850L 2.4/5 GHz 2T3R transceiver. The radio, however, is locked to single-band 2.4 GHz operation. The processor could not be determined due to a soldered-in radio module over an RF shield. It does not appear Ubicom-based, however, since Ubicom's signature automatic QoS features are not present in the 685.
The WAN port and four LAN ports are handled by a Realtek RTL8366 Gigabit switch that appears to have support for jumbo frames up to 9K enabled. There is also a small, extremely loud fan that ran constantly during throughput and NAS testing.
Other wireless features include WEP, WPA and WPA2 (both "Personal" and "Enterprise") wireless security, Wi-Fi Protected Setup (WPS) and Guest WLAN with separate traffic, SSID and security settings.
Routing throughput was the fastest we have ever seen with 659 Mbps WAN to LAN and 703 Mbps uplink. Maximum simultaneous sessions maxed out at our test limit of 200.
Best-case (Location A) maximum wireless throughput in the default 20 MHz bandwidth mode measured 78.9 Mbps running downlink and 69.8 Mbps uplink averaged over a 1 minute test. Switching to 40 MHz mode improved throughput to 111.4 and 97.6 Mbps for down and uplink, respectively. Throughput dropped very quickly with distance, however. Although the Intel 5300 test client remained associated in all locations, throughput was not high enough to complete testing in the lowest-signal test locations.