These next few settings technically aren't related to QoS, but configuring them correctly can help ensure your wireless network is operating as fast as possible for your environment.
First, determine the fastest protocol that all your network devices can handle. If everything is capable of 802.11n, for example, click Setup in the horizontal menu bar, click Wireless Settings in the vertical menu bar on the left side, and then click the Manual Wireless Network Setup button.
Look under the heading Wireless Network Settings and change 802.11 Mode to "802.11n only." If your gear is a mixture of 802.11g and 802.11n products, choose that option instead, or whichever option is appropriate for your devices. (The DIR-655, like many other routers, can support mixed b/g/n, mixed g/n or mixed b/g.) The objective is to configure your network to operate on the highest common denominator to take full advantage of all your hardware's capabilities.
A word of warning: If you change your router to operate in 802.11n-only mode and one of your devices suddenly stops working, it might not be 802.11n compatible, in which case you'll need to change the router back to support a slower standard if you want to continue using that device.
Next, set Transmission Rate to "Best (automatic)" and set Channel Width to "Auto 20/40 MHz." (Note: Your router might not have either of these settings, or it might use different terms to describe them. Belkin, for instance, doesn't allow you to change the transmission rate on some of its routers, and it refers to channel-width settings as "bandwidth.")
Channel bonding can significantly increase your router's wireless performance.
Changing Channel Width in this manner will increase your router's wireless bandwidth by bonding together two of the three non-overlapping 20MHz channels available in the 2.4GHz frequency band. If there are 802.11b or g wireless networks operating in close proximity, the router should automatically revert to using a single channel, abiding by the so-called "good neighbor" policy. (Channel bonding can drastically slow or even shut down neighboring Wi-Fi routers by consuming all the available wireless bandwidth.)
Belkin routers refer to channel-width settings simply as Bandwidth.
This issue largely disappears with newer dual-band routers that are equipped with both 2.4- and 5GHz radios, because there are 12 non-overlapping channels (23 channels worldwide) available on the 5GHz frequency band. Unfortunately, most older wireless media players are outfitted only with 2.4GHz receivers.
Click the "Save Settings" button when you've made all your changes.