It usually goes like this: the network runs smoothly until a certain hour, then starts stuttering. The first assumption is almost always the same, someone must be downloading something enormous.
Limiting speed per device sounds like the answer. Sometimes it is, but more often it is not, and telling the difference saves a great deal of time.
First, confirm this is actually the problem
Before changing any setting, there are three other causes that are far more common and are not helped at all by throttling.
| Symptom | Likely cause |
|---|---|
| Slow at the same hour every day | Congestion at the provider, not your users |
| Full signal but still slow | Band or channel, not capacity |
| Only one device is slow | That device itself |
| Slow for everyone when busy | Now this is about sharing capacity |
Only the last row is genuinely answered by throttling. For the first, the cause sits outside your network, guide to the internet being slow at certain hours. The second is covered in the guide to full signal but slow internet, and the third in the guide to Wi-Fi trouble on one device.
The common misunderstanding. A device downloading a large file does use a lot of capacity, but it yields reasonably well when other devices ask for some. What really ruins the experience is queueing: and that comes more often from uploads than downloads. The distinction is explained in the guide to bandwidth, latency, and throughput.
Finding the feature
The name differs by brand. Look for one of these in the router's admin pages:
- QoS: the most common name
- Bandwidth Control or Traffic Control
- Parental Control: on some routers, speed limits live here alongside time limits
- Smart Queue or SQM: this one is different, and is actually the most useful
If none of them is present, your router simply does not support it. Cheap routers often leave this feature out, and there is no way to add it short of replacing the hardware.
Setting a per-device limit
Identify the device first
Open the list of connected devices. The names shown are often unhelpful, so match by MAC address instead, the same method as in the guide to blocking a Wi-Fi user.
Give that device a fixed IP address
This is the step most often skipped, and the result is a rule that quietly stops working. If the device's address changes, the limit attaches itself to a different device instead, the problem is explained in the guide to local IPs, DHCP, and address clashes.
Enter the download and upload limits
Watch the units. Some routers want the figure in kilobits rather than megabits, misread it and you set a limit a thousand times smaller than intended.
Test from the device you limited
Run the speed test on that device itself, not another one. If the figure has not changed, the address usually does not match the one you registered.
Reasonable figures
| Use | Adequate limit |
|---|---|
| Browsing and messaging apps | 1–2 Mbps |
| Standard-quality video | 3–5 Mbps |
| Video calls | 4–8 Mbps, at least 3 upload |
| High-quality video | 15–25 Mbps |
For visitors at a business, 3 to 5 Mbps per device is plenty. Dropping below 2 Mbps makes the experience feel broken, and the complaints that follow are usually more trouble than the problem you set out to solve.
Prioritising rather than limiting
For most situations this is the better approach. Instead of holding some devices back, you raise the priority of the ones that genuinely matter.
Worth prioritising: the till, devices used for video calls, and payment terminals. Usually not needed: smart televisions and games consoles, both buffer, and neither suffers from a brief pause.
If you are prioritising for online gaming, note that what matters there is steady latency, not raw capacity. The limits of dedicated hardware for that are discussed in the guide to whether a gaming router is worth it.
The feature that helps more than a numeric cap
If your router offers Smart Queue or SQM, try that before setting any limits at all.
It works differently. It holds nobody back; instead it orders the queue so that no single stream can fill the pipe and leave everything else waiting. The effect is often more noticeable than limiting devices one by one, particularly on connections where the upload speed is far smaller than the download, which is the norm in Indonesia.
For a business
Per-device limits get unwieldy as visitor numbers grow. The two approaches below hold up better.
Separate the networks. Give the guest network its own share of capacity, so operations are never affected however busy it gets, guide to separating a guest network.
Limit by session, not by number. Vouchers with an expiry solve the lingering-visitor problem without touching speed settings at all, guide to setting up Wi-Fi vouchers.
Do not throttle a work device without checking what it is doing. Network printers, scanners, and file-sharing computers sometimes appear to use a lot of capacity while doing work that genuinely needs doing. Limiting them makes printing stall with no error message, guide to sharing a printer over Wi-Fi.
When the limit does not take effect
- The device's IP address changed. The most common cause. Assign a fixed address first.
- The rule was made on the wrong band. On some routers, 2.4 GHz and 5 GHz keep separate lists.
- Units misread. Kilobits and megabits differ by a factor of a thousand.
- The device uses a random MAC address. Modern phones disguise their address per network, so an older rule no longer recognises them.
- There simply is not enough capacity. If your subscription is already full before anyone overuses it, limiting only divides the shortfall, guide to choosing an internet plan for a business.
For a desktop connected through a Wi-Fi adapter, check too that its speed is not being capped by its own hardware, something often mistaken for router throttling, guide to choosing a USB Wi-Fi adapter.
Frequently asked questions
Can every router limit speed per device?
No. The feature is usually called QoS, Bandwidth Control, or Traffic Control, and many cheap routers do not have it at all. Some offer only a coarse priority setting with no adjustable limit.
Why does the network still feel slow after setting limits?
Because what makes a network feel slow is often not the size of a download but the queue. A single device uploading continuously can make everything feel sluggish while using very little capacity. The feature that helps with this is usually called Smart Queue or SQM.
Is it better to throttle speed or separate the networks?
For a business, separating the guest network from operations is almost always the better answer. A numeric cap holds back excess use, but separation guarantees the till and the work computers are never affected in the first place.
What is a reasonable limit for guest users?
Around 3 to 5 Mbps per device is enough for browsing, maps, and standard-quality video. Dropping below 2 Mbps makes the experience feel broken, and the complaints that follow are usually more trouble than the original problem.
