Fix guide
Does QoS actually reduce ping? What it fixes and what it cannot
QoS is sold as a gaming feature and usually configured so badly that it does nothing. Configured properly, it is the most effective free fix for one specific symptom: latency that spikes when the connection is busy.
What it actually does
QoS decides which packets get sent first when the line is full, and SQM keeps the queue short instead of letting it grow. A short queue means low delay under load. On an idle line QoS changes nothing at all — there is no queue to manage.
The number almost everyone gets wrong
SQM needs your real upload and download rates, set slightly below what your line actually delivers (typically 85–95%). If you enter the advertised speed instead of the measured one, the queue still builds and your spikes continue. Measure with a wired device, then enter the measured number.
When it will not help
- Your line is idle and latency is still high — that is distance or routing, not queues.
- Your ping is stable and high — again, distance or routing.
- The spikes come from Wi-Fi retransmission, not from the queue. QoS on the router does not fix a bad wireless link.
- The congestion is upstream of your router, in the neighbourhood or the provider network.
The honest verdict
If your test shows latency rising sharply while the line is busy, enabling SQM at the correct rate is worth doing before any purchase. If it does not show that, QoS is not your problem and neither is the product someone is trying to sell you.
