Understanding your router's QoS settings
QoS (quality of service) is one of those router features that sounds like it should be a magic switch: flip it on, and suddenly your Zoom calls stop glitching while someone else is downloading a game update.
In reality, QoS works best when you understand what problem you’re solving. Most “my internet feels bad” moments at home aren’t caused by your Wi‑Fi being slow. They’re caused by latency spikes when your connection is busy, which is exactly what QoS can help with.
QoS in plain English
Your home network has a few choke points. Usually the tightest one is your internet connection, especially upload. When someone saturates that link (cloud backups, big uploads, a console patch, a bunch of smart cameras), packets start waiting in line.
Without any traffic management, many routers/modems will happily build a huge “waiting room” (a queue). That’s called bufferbloat, and it’s why everything else suddenly feels laggy even though your speed test looks fine.
QoS is your router trying to manage that waiting room so interactive stuff (video calls, gaming, browsing) doesn’t get stuck behind bulk transfers.
If you want a deeper “why,” Bufferbloat.net has excellent explanations and practical tuning notes. Their SQM guide is a great reference: https://www.bufferbloat.net/projects/bloat/wiki/Getting_SQM_Running_Right/
The QoS settings you’ll usually see (and what they really do)
Router interfaces vary a lot, but the common knobs fall into a few buckets.
Bandwidth limits / shaping (often the most important). If you tell your router your real speeds, it can shape traffic so your router becomes the bottleneck instead of your modem or ISP equipment. That’s the trick: you want the queue to live in the device you control. In practice you usually set the limits a bit below your measured speeds so shaping actually “catches” the congestion.
Device or application priority (“gaming,” “work,” “streaming”). This can help, but it’s easy to overdo. Many routers guess traffic types, and encrypted traffic makes guessing harder. Start simple (one or two priorities) and only add rules if you can describe the exact problem you’re fixing.
SQM / CAKE / fq_codel (the “good QoS”). Some routers (and firmware like OpenWrt) offer modern queue management that’s built specifically to keep latency low under load. CAKE is designed to minimize bufferbloat and keep traffic fair with relatively little tuning: https://help.mikrotik.com/docs/spaces/ROS/pages/196345874/CAKE
WMM (Wi‑Fi Multimedia). This is Wi‑Fi-side prioritization. It can help on the wireless link, but it doesn’t replace WAN-side shaping. You can have WMM enabled and still get slammed by upload congestion.
DSCP / DiffServ / packet marking (advanced). These are “priority labels” in packets. They can be useful inside your own network, but typical home ISPs won’t honor markings end-to-end, and many apps/devices don’t mark consistently.
A sane way to set up QoS (without getting lost)
You don’t need to become a network engineer to get most of the benefit. Here’s a practical approach that works across a lot of routers.
Start with a bufferbloat test, not just a speed test. You’re looking for latency under load. Waveform’s bufferbloat test is an easy baseline: https://www.waveform.com/tools/bufferbloat
Enable QoS/SQM and set bandwidth limits manually. Use real-world speeds, but start a bit under your maximum, especially on upload.
Test again and adjust. If latency under load is still bad, lower the configured bandwidth in small steps. If latency is great but speeds are clearly lower than expected, raise the numbers slightly.
Add one simple priority rule (optional). Examples: give a work laptop higher priority, or deprioritize a device that does big uploads (NAS backups, torrents).
Re-test when things change. New ISP, new modem, new router, or a plan upgrade means your bottleneck moved, so your tuning should too.
Common mistakes that make QoS feel “broken”
- Setting bandwidth to the advertised plan speed. Your real speed varies, and shaping needs headroom.
- Ignoring upload. Upload is where home networks often fall apart.
- Building a dozen complex rules. More rules means more misclassification and more mystery.
- Expecting miracles from an underpowered router. Some QoS/SQM features are CPU-intensive.
- Running QoS in two places. If your ISP gateway and your router are both doing traffic shaping, results can get unpredictable.
When QoS won’t help (or isn’t worth the effort)
QoS can make a big difference when you’re fighting latency under load. It can’t create bandwidth out of thin air.
If your household regularly needs more upload than you actually have (cloud backups plus video calls plus big uploads), QoS can keep things from melting down, but you may still feel constrained. In that case the real fix is either changing habits (scheduling big uploads) or upgrading service.
One last practical note: the “best” QoS setting is the one you don’t have to think about. Aim for noticeable improvement in call quality and responsiveness, not a perfectly optimized set of rules.