Why is internet much faster over a cable than over Wi-Fi?

The two tests use different paths between your device and the network: the cable test skips the wireless part, while Wi-Fi depends on the signal reaching your device. Wi-Fi performance can vary with location and home layout, and 2.4, 5, and 6 GHz bands are relevant when comparing results. [S1] Weak signal, physical obstructions, and wireless interference are also possible contributors. [S2]

That makes the Wi-Fi link a reasonable place to investigate, but the gap alone does not identify one cause. The supplied guidance does not quantify how much faster a cable should be, establish that cable is always faster, or explain the limits of every device.

Start over with a small, repeatable comparison. Use the same device and speed-test method for both connections, and test them close together in time. Keep a note of the result and which connection you used. If you cannot use the same device for both, write down which devices you used; that leaves device differences as an unresolved variable rather than proving Wi-Fi is the cause.

For Wi-Fi, record where you were and, if you can see it, which band the device used. Microsoft recommends measuring at multiple places in the home before making changes and retesting afterward under comparable conditions. [S1] You do not need to change settings to get a useful first picture.

Compare Wi-Fi results in the room where you use the device and in a location closer to the router, keeping the device and test method the same. Note whether the result changes with location. Home layout, band, weak signal, obstructions, and interference can all matter to Wi-Fi performance. [S1][S2]

If your device shows whether it is using 2.4, 5, or 6 GHz, record that too; the Microsoft guidance discusses all three, while Apple’s cited guidance discusses 2.4 and 5 GHz. [S1][S2] Do not treat a band label by itself as a diagnosis. The source extracts do not say which band will be fastest in every room or for every device.

Use a short log rather than changing several things at once. For example, these are placeholders, not real test results:

1. Test A: cable; device [same device]; place [desk]; time [time]; result [value and units].
2. Test B: Wi-Fi; device [same device]; place [desk]; band [shown or unknown]; time [near Test A]; result [value and units].
3. Test C: Wi-Fi; same device; place [near router]; band [shown or unknown]; time [time]; result [value and units].
4. Retest after one change: [describe change]; place and test method [same as before]; result [value and units].

If Wi-Fi results differ by place, record that pattern and consider the room conditions before making further changes. If they do not, the available evidence here cannot identify the cause; device capability or other parts of the setup may need checking. This guide’s sources do not establish a particular speed threshold or diagnose your equipment.