How-To Geek

The Beginner’s Guide to Using QoS (Quality of Service) on Your Router


We’ve covered QoS before when we showed you prioritize your DD-WRT router’s traffic and in our 5th tip for getting the most out of Tomato. It’s a little more complicated than creating rules, so let’s see how things work.

What Is QoS?


QoS, or Quality of Service, is a method for controlling traffic priority on networks. It works on all levels of network activity, but for our purposes, it’ll be centered around your home router. There, QoS kicks in when there’s a bottleneck and decides which traffic is more important than the rest. Exactly what is more important then the rest is based on rules that you supply. You can specify importance based on criteria such as IP address, MAC address, and even service name.

Where’s the Bottleneck?

Many people set up QoS hoping that it’ll do a lot of good only to report later that it doesn’t do anything. That’s because QoS only works when the bottleneck is in the right place, and the key settings are your bandwidth declarations.

bandwidth 1-01

Suppose that your QoS settings are set beyond the bandwidth you receive from your ISP. What happens is that the traffic that leaves your router isn’t prioritized because your router thinks that there’s ample bandwidth available. Meanwhile, you’re hitting your ISP’s caps, and they’re the ones who decide what is and isn’t important.

On the other hand, if you set your QoS’s declared bandwidth lower than your allotted ISP bandwidth, you’re creating an artificial bottleneck where you can control it: at your router. Now, your own QoS settings kick in and re-arrange your traffic. The cost of bandwidth is pretty minimal, but by tweaking things slowly you can marginalize it further.

Tweaking Steadily

The key to getting your bandwidth back is tweaking and observing over time. The Uplink and Downlink settings are your keys.


Start by taking a bandwidth test to find out what your normal speeds are from your ISP. There are numerous tests out there, such as Speakeasy Speed Test and

bandwidth test 2

bandwidth test 1

We suggest you start your QoS dabbling by setting these values to 85% to ensure that your QoS is being effective. Once you tweak your settings until things work the way you want them, you need to take the next step and ramp things up bit by bit.

Take your Downlink and Uplink and boost them by 1-2% at a time, preferably while maxing out your bandwidth and checking your QoS settings to make sure they’re still in effect. It’s possible to go as high as 95% percent and still have your bandwidth prioritization working. Kick things up by an increment and give it a few days. Lather, rinse, repeat. You can reclaim quite a bit of sacrificed bandwidth this way.

Yatri Trivedi is a monk-like geek. When he's not overdosing on meditation and geek news of all kinds, he's hacking and tweaking something, often while mumbling in 4 or 5 other languages.

  • Published 09/29/11

Comments (13)

  1. nrew

    Do you have psychic powers? I was just planning to buy a router with QOS features. Thanks for this yet another timely guide!

  2. Luis Vázquez

    Thank you! I had to uninstall dd-wrt from my router just because I didn’t knew how to set up QoS.

  3. geeknik

    IMO, I think the QoS settings in Tomato are better than DD-WRT.

  4. Wayne

    I don’t even bother myself. Thought about it but haven’t noticed any slowdowns even when 2 or 3 people are streaming HD video. Then again, my internet speed is ~30 Mbps down and ~5 Mbps up. Of course, I pay Time Warner a lot for this speed as well. $80.99 a month. However we use a lot of bandwidth in my house. Right now we’re at 163,398 Megabytes for the month. We’re an internet heavy household. Only one television but we have 15 IP connected devices that can stream music and video. I am just glad that I upgraded the entire house to Gigabit Ethernet.

  5. Todd

    I think Wayne came on here to brag.

  6. Wayne

    Maybe… However there is more to the point. If you call Time Warner and ask for Internet Service, they won’t offer my package. They will offer the basic package that everyone gets. You have to ask about the higher level packages. As bandwidth pipes get fatter, workarounds like QOS become less relevant. If people want really great access, they should contact their providers and see what the better packages cost. Geeks really shouldn’t have to settle for basic service.

  7. JEB

    I have 90 MB upload & download speeds in Jackson, TN for $90 a month

  8. Wayne


  9. Jeffery

    Mine is 100Mbit/s down with 50Mbit/s up at 50+ Singapore Dollars.. :)

  10. Jack

    Chattanooga TN has fiber to the houses available. Up to 1G I think. But with fiber, 10G could be available, if you have the $$$ to pay for the bandwidth! Most mortals go with something less to keep the bills down. I think the provider is the local government rather than a ‘for profit’ vendor.


  11. surendar


  12. bob

    @Wayne internet speeds faster than 30Mb/s are very easy to get nowadays. I have 50Mb/s in the UK, could go to 100Mb/s when it becomes available in my town (it already is in many parts of the UK).

  13. Menace

    Most home use routers don’t have the cpu power to handle modern connection speeds with qos.
    for instance on my Netgear wndr3700 with DD-wrt with QOS enabled I get the full 100/5 mbit when I enable qos with the propper settings I max out at about 75 mbit.

    If I do the same thing on an asus wl500G deluxe or linksys wrt54g2 I get stuck at 30 mbit with qos and 85-90 without both loaded with dd-wrt.

    On my PIII Celeron 733 X86 dd-wrt router up to about 450 mbit both ways isn’t a problem with qos enabled.

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