Test once right next to the router with other downloads paused, then once in the room where things feel slow. The gap between those two results usually tells you more than either number on its own. And look past download: upload, ping and jitter are what calls and games care about.
Do it in this order
- Pause what you can on other devices — streaming, backups, game updates.
- Stand about a metre from the router and run the test. That is your best case.
- Walk to the room where the problem happens and run it again on the same phone.
- If the trouble only shows up in the evening, repeat both tests then.
Write down all four numbers each time — download, upload, ping and jitter. People usually keep only the first one, and it is rarely the one that explains a choppy call.
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The four numbers, briefly
Download is how fast things reach you; it matters for streaming and downloads. Upload is the reverse and matters for video calls and photo backups — it is often much lower than download, and that is normal on many plans. Ping is the time for one round trip, in milliseconds; under about 30 ms feels snappy. Jitter is how much that delay jumps around; above about 30 ms, voices start to break up.
There is a fifth number worth knowing: delay under load, the ping while the line is busy. If it climbs by more than about 100 ms, calls will stutter whenever someone else downloads — even on a fast plan.
Remember that plans are sold “up to” a speed, and a phone on Wi-Fi rarely reaches the full speed of a fast fibre line. Judge the result by how the connection behaves, not only by the number on the contract.
Frequently asked questions
Why is my result lower than my plan?+
Plans are sold as “up to” speeds, and Wi-Fi, your phone, other devices and the time of day all take a share. Test next to the router with everything else paused to see your best case.
Does a speed test use mobile data?+
Yes, when you run it on mobile data. In Diagnostix360 the speed test is optional: up to 170 MiB for the full test and 55 MiB for the quick one, and the app tells you before it starts.
My speed is good, so why does it feel slow?+
Speed is only one measurement. High ping, jitter, packet loss or a delay that jumps when the line is busy can make a fast connection feel slow.
One test is a snapshot
Diagnostix360 keeps every result, so you can put the morning test next to the evening one. If the problem comes and goes, Live Monitoring keeps measuring for up to 90 minutes and notes when it drops.
This article is general troubleshooting information, not professional, contractual, legal or SLA advice. The ranges are practical references, not certified pass/fail standards. Results vary with the device, network and time of day. Diagnostix360 describes conditions measured at that moment; it does not assign responsibility. See the Terms of Use and Privacy Policy.