You might have heard of QoS, which is short for Quality of Service. It’s a common and practical feature among home Wi-Fi routers.
This post will help you understand when Quality of Service applies, what you can expect from it, and what you cannot.
It’s all about managing your bandwidth. While QoS can apply to traffic between local devices, this post mainly discusses the Internet connection.
Dong’s note: I first published this post on March 23, 2020, and updated it on May 5, 2025, with additional relevant information.
QoS explained: What is the Quality of Service?
Quality of Service is a routing feature that allows users to prioritize the bandwidth for specific programs, clients, or services.
In a nutshell, the way it works is that QoS takes the existing broadband connection and designates a specific amount of requested bandwidth to your desired target(s) in real-time before the rest of the network. Having the first dibs on the bandwidth, the prioritized parties also enjoy the best possible connection quality, including the lowest possible latency.
For example, if you prioritize VoIP, your Internet-based calls will get all the bandwidth they need before any other applications. Or, if you prioritize your Xbox (or a particular game), the game console will get first access to the Internet before any other devices.
You can do that with anything you want, such as streaming on Netflix, video calling, browsing the internet, and so on.
Of course, you can also prioritize file downloading, though you shouldn’t. Downloading never requires prioritizing. Instead, it’s generally the reason we need QoS in the first place.
Indeed, when left alone, a single file download job may consume all the bandwidth, regardless of the Internet connection speed, until it is complete.
So, QoS is also about giving specific devices or services the lowest priority on the broadband to ensure they won’t interfere with the regular and more critical operation of the rest of the network.
When properly configured, QoS can make everyone happy when a modest broadband connection is shared between a large group of active devices.
“Smart Queue Management” (SQM) and “Bufferbloat”
You might have heard of the two terms above, with the former as the solution to fix the latter.
It’s worth noting that Bufferbloat used to be a prevalent issue with legacy Internet connections, such as DSL hardware. Nowadays, it’s a rare occurrence with fast broadband, and the function of SQM is generally incorporated within modern routers’ QoS features, often under different technical terms.
Still, “Smart Queue Management” (SQM) and “Bufferbloat” have been widely used, often in vague or ambiguous ways, in online clickbait content and certain hardware vendors’ marketing campaigns. In most cases, they are as irrelevant and overhyped as the dBi value of a Wi-Fi broadcaster.
When Quality of Service applies, and when it doesn’t
As mentioned above, QoS is about prioritization. So, you only need it in situations where prioritizing is required.
And when is that?
We need to prioritize when the broadband bandwidth is insufficient for all online applications of a local network to run simultaneously. That’s when the Internet speed is the bottleneck.
The faster your Internet and the fewer applications you have, the less likely you’ll need QoS. The precise ratio depends on the situation, but based on my experience, the following are the degrees to which QoS applies, depending on the Internet bandwidth.
- 100Mbps or slower: You likely need QoS.
- Between 100Mbps and 500Mbps: It’s generally a good idea to have QoS.
- Between 500Mbps and 1Gbps: You mostly don’t need QoS, but it’s a good idea to have it when there’s a file-sharing station, such as BitTorrent, within the network. You need to give this device the lowest priority.
- Between Gig+ to 2.5Gbps: You don’t need QoS unless you have multiple file-sharing stations.
- Faster than 2.5Gbps: It’s better to turn QoS off. Having it on likely only makes things worse.
In short, QoS is generally only applicable when the Internet bandwidth is less than what you’d like it to be. If you have super-fast broadband, this feature is generally not necessary.
When you have 10Gbps Internet, the local network connection to each device is the bottleneck—they all have much slower connection speed anyway, be it a Gigabit wired connection or Wi-Fi. As a result, QoS is no longer necessary.
Internet speeds vs. QoS: Mind the gap!
It’s important to note that QoS is not about making your Internet speed fast(er)—you wish! It’s about giving the device or service at hand what it needs when it needs it and possibly not more.
Consequently, when you turn on QoS, you’ll almost always get slower speed test results. And that’s the point because speed testing, which is raw data downloading, is not how we generally use the Internet. Keep that in mind.
Also, when you misconfigure QoS and set its download speed significantly lower than your broadband’s actual speed, the pre-determined QoS speed will be the ceiling for the entire network.
That said, if you have turned QoS on in your router and now upgrade your Internet to a faster grade, it’s important to readjust your QoS settings. Otherwise, you’ll continue to experience the old connection speed.
What you need to use QoS
You generally need two things to take advantage of QoS.
First and foremost is a router that supports this feature. Most, if not all, home Wi-Fi routers have QoS, but the way they do it varies from one vendor to another. There are a lot of degrees and nuances when it comes to this feature.
In my experience, Asus routers support this feature well and allow for easy configuration. Those Linksys, Netgear (select models), and TP-Link are also quite good. However, the most comprehensive QoS is from Ubiquiti’s UniFi consoles since they are enterprise-grade hardware.
Secondly, you need to know the speed and quality of your Internet connection. It’s pretty easy to find out—I wrote a long piece on speed testing if you need to know the exact numbers and what they mean. Some routers have speed test functions explicitly designed to work with their QoS features.
Tip
It’s best to know your exact broadband speeds when setting up QoS, which can be tricky.
That said, keep in mind that it’s OK to use a slightly lower speed for your QoS. So if you have 500Mbps for download, you can enter 450Mbps.
However, it’s never good to use a higher number. (Like 550Mbps for a 500Mbps plan). In this case, QoS might produce no meaningful result at all. It can even make things worse.
The rule is this: Set your QoS to use as close to the exact broadband bandwidth as possible, but not above that.
With that, let’s set the right expectations on what you can get out of your QoS-enabled Internet.
Quality of Service: Different types of QoS
Quality of Service comes in many flavors, but among consumer-grade routers, there are generally two types of prioritization: by device and by application.
For the former, a router can give a few connected clients the highest priority and keep the rest of the network at the lower tiers. When a device is on the list, it’ll get all the bandwidth it needs before others.
Prioritization by application is a more sophisticated and holistic approach. If an application or service is on the prioritized list, it will get the best connection across all network devices.
Most gaming routers support application-based prioritization, and more often than not, if a router has application-based prioritization, it can also handle the device-based option.
Advanced hardware, such as a UniFi router as mentioned above, can do even more, such as customizing prioritization by specific traffic source, applications, time of day, and so on.
Setting the right expectations with QoS
For QoS to be adequate, your Internet connection must be at least as fast as, or better yet, faster than what is needed by the prioritized party. So, if your application needs 25Mbps of download speed and your broadband caps at 20Mbps, no QoS can help you in this case.
I picked 25Mbps for a reason. That’s the download speed required for streaming 4K content on one device from Netflix or any other service. So, if you’re suffering from buffering and wait time while streaming over a modest Internet connection, don’t immediately blame your Wi-Fi for it—they are two different things.
Also, QoS can not improve the quality of your Internet connection.
For example, if your broadband has high latency (lag), which is terrible for real-time communication, QoS won’t improve that. All it can do is give a particular application, service, or client within your network the best possible experience within what you get from the service provider.
Still, real-time communication applications, such as Internet-based calling and online gaming, benefit the most from QoS.
Final thoughts
Internet traffic is somewhat like cash flow for a household (or a business)—it’s all about managing its right and staying on budget. And that’s where Quality of Service comes into play.
Again, this feature is about giving a device the bandwidth it needs (and no more) when it needs it. It does not make your Internet faster.
QoS is about degrees and nuances. When you configure it correctly, you’ll be surprised how little Internet bandwidth you actually need. However, in a poorly configured network, even Gigabit broadband is not consistently fast enough for every device.
