Why is my WiFi slow even though my internet plan is fast?
The speed you buy is delivered to your router. What reaches your laptop is whatever survives the wireless link, and those two numbers are frequently very different. Testing over a cable is the fastest way to tell which half of the problem you have: if the wired speed is close to your plan, the connection is fine and the wireless is the bottleneck.
Several things degrade wireless throughput, and they compound.
- Distance and obstacles. Signal weakens with distance and is absorbed by walls, especially those containing brick, concrete, foil-backed insulation or plumbing. A router in a cupboard on one side of the house is a genuine cause rather than a technicality.
- Interference from neighbouring networks. In flats and dense streets, many networks compete for the same channels. The lower frequency band travels further but is far more crowded and offers less capacity.
- Band selection. The higher frequency band carries much more data but has shorter range and penetrates walls poorly. A device that clings to the lower band because it is nominally stronger will be slow even standing near the router.
- Older devices. One device connecting with an old wireless standard can reduce efficiency for others sharing the same radio.
The fixes in order of effect are usually moving the router somewhere central and unobstructed, encouraging devices onto the higher band, choosing a less congested channel, and only then considering new hardware or a mesh system.
It is also worth checking what else is using the connection. A single device performing a large backup or download will consume most of the available capacity, and the wireless link is not the culprit at all.