The Wi-Fi guarantee reality check
Beyond the speed test
A home can meet its provider's guarantee in every room and still have Wi-Fi that drives everyone mad. That isn't anybody being dishonest — it's that a single speed test measures one thing, at one moment, in one spot, and almost none of the things that actually go wrong.
What a room speed test does and doesn't tell you
| What matters | Measured by the test? | Why it matters |
|---|---|---|
| Throughput (the big number) | Yes | How much data can move at that moment, in that spot. |
| Latency | No | The delay before anything happens. This is what ruins calls and gaming. |
| Jitter | No | Whether that delay is steady. Wobbly delay makes voices break up. |
| Packet loss | No | Bits of data that never arrive, causing freezes and drop-outs. |
| Coverage over time | No | A test at 11am says nothing about 8pm when everyone is home. |
| Roaming | No | Whether your phone hands over cleanly as you walk between boxes. |
| Device reliability | No | Whether a doorbell or speaker stays connected all day. |
| Mesh quality | No | How well the boxes talk to each other, especially without a cable. |
| Interference | No | Neighbours' Wi-Fi, baby monitors and microwaves. |
| How apps actually feel | No | The thing you actually care about. |
Is the guaranteed speed enough for your house?
Roughly what everyday things need, so you can judge a 3, 10, 30 or 100 Mbps promise for yourself.
| What you're doing | Roughly needs | Worth knowing |
|---|---|---|
| Video call for work | 5–10 Mbps | But it needs steady delay far more than it needs speed. |
| 4K film | 25 Mbps | Per stream. Two tellies doubles it. |
| Cloud backup | 20 Mbps+ | Mostly upload, and it runs in the background. |
| Online gaming | 5 Mbps | Speed barely matters; delay and packet loss decide it. |
| Busy family evening | 80–150 Mbps | Two streams, a call, a console and a dozen smart gadgets. |
| Smart home | Under 1 Mbps | Almost no speed, but it must never drop. |
Four times a room passes and life still doesn't work
- A 3 Mbps promise met at 11am. By 8pm, with the family home and the neighbours streaming, the same room is unusable. Nothing in the guarantee covers time of day.
- 30 Mbps in a bedroom on a gigabit package. The promise is kept. You're getting three per cent of what you pay for in that room.
- The Sonos drops but the speed test passes. Speakers and doorbells fail on things a speed test never looks at: how devices are discovered on the network, and whether they can rejoin cleanly.
- Video calls break up at 200 Mbps. Plenty of speed, unsteady delay. The number looks great and the call is still awful.
What we look at instead
Throughput, latency, jitter, packet loss, coverage, roaming, device reliability, mesh quality, interference and whether your actual apps behave. That's the whole point of asking what's wrong rather than reading one number.