The short answer
Test wired, not over Wi-Fi, because Wi-Fi is almost always the limiting factor and providers will dismiss a wireless test immediately. Plug a computer directly into the router with Ethernet, stop all other traffic, and test several times across different hours. If the wired figure is close to the advertised speed, your problem is inside the house.
Advertised broadband speeds are measured at the router, wired, with nothing else running. Almost nobody tests that way, which is why complaints frequently do not survive contact with the provider. Establishing what you are actually getting is straightforward and worth doing before anything else.
How to test properly
Connect a computer to the router with Ethernet
Straight into the router, not through a switch, a powerline adapter or a hub. Use a Cat 5e or better cable.
Stop everything else
Pause cloud sync, close streaming, and ideally disconnect other devices or turn Wi-Fi off on the router temporarily. One large download elsewhere in the house invalidates the test.
Use more than one test service
Run a well-known speed test, and also your provider’s own test if they have one, since that is the figure they will accept.
Test at several times of day
Morning, afternoon and about 9pm. The difference between those is what identifies congestion versus a line fault.
Record the numbers with timestamps
Download, upload and latency, with the date and time. A log across a week is far more persuasive than a single result.
Note whether the computer can even reach that speed
An older laptop with a 100 megabit network port cannot exceed 94Mbps regardless of your connection, and this catches people out on gigabit packages.
Providers advertise average speeds, typically the figure at least half of customers receive at peak time, and your contract will state a minimum guaranteed speed. That minimum is the number that matters if you want to escalate, because falling below it usually triggers an obligation to fix it or let you leave.
If the wired speed is fine
Then the connection is delivering and the problem is between the router and your device. In order of likelihood:
- Wi-Fi distance and walls. The most common cause by far. Test standing next to the router and again where you normally sit, and compare.
- Band. A device on 2.4GHz will be slow regardless of your package. Check which band it is using.
- Channel congestion, particularly in flats and particularly in the evening.
- An old device. A laptop with an 802.11n adapter cannot exceed a fraction of a modern connection no matter what the router does.
- The router itself, if it is several years old or supplied free by the provider.
- Too many devices, where the router’s processor rather than the connection is the bottleneck.
If the wired speed is also low
Now you have something to take to the provider. Before calling, check a few things that can cause it at your end:
- The master socket. On a connection using phone wiring, testing at the master socket with internal extensions disconnected eliminates house wiring as a cause. Providers will ask.
- Cable quality and joints between the wall and the router.
- Router firmware, which occasionally causes throughput problems and is worth updating before escalating.
- Router in modem mode combined with your own router, which can create a bottleneck if the second device is underpowered.
- Whether the line has been capped, which some technologies do automatically after repeated errors and which the provider can reset.
Check your actual package before complaining. People frequently misremember what they signed up for, or are on a legacy package that was never upgraded. The account page will state the speed you are contracted to receive, and comparing against the advertised speed of a package you do not have wastes everyone’s time.
Making the complaint effective
Providers respond to specifics. A log of wired speed tests with timestamps, including tests on their own testing service, showing consistent results below the guaranteed minimum, is very difficult to dismiss. Mention that the tests were wired, at the master socket where relevant, with other devices disconnected, because those are the objections they will otherwise raise.
If the pattern shows good speeds off-peak and poor speeds in the evening, that is contention on their network rather than a fault on your line. It is a different conversation and worth naming explicitly, since the resolution is capacity investment rather than an engineer visit.
What to fix yourself
If the wired speed is good and Wi-Fi is the limit, the useful changes are, in order: move the router out into the open, put important devices on 5GHz or 6GHz, choose a clear channel, wire anything that does not move, and add a mesh node if coverage is genuinely the issue. Replacing the provider’s router with your own is often the single biggest improvement in a house with a basic supplied box.
Why is my Wi-Fi speed lower than my broadband speed?
Because Wi-Fi has its own limits: distance, walls, band, channel congestion and the age of the device’s adapter. It is normal to get a fraction of your line speed at the far end of a house.
Should I test over Wi-Fi or Ethernet?
Ethernet, for any test you intend to act on. A Wi-Fi test measures your Wi-Fi, not your broadband, and providers will correctly dismiss it.
What speed do I actually need?
Around 25Mbps per 4K stream, and far less for everything else. Most households are limited by Wi-Fi and latency rather than by total bandwidth, which is why upgrading a package often changes nothing.
Why is it slow only in the evening?
Either neighbouring Wi-Fi congestion, which you can fix by changing channel, or contention on the provider’s network, which you cannot. Wired tests at both times distinguish the two.
Does a new router increase my speed?
It can raise the speed devices actually achieve over Wi-Fi, which is often what people mean. It cannot exceed what the line delivers, so test wired first to see which limit you are hitting.
The short version
Test wired, with nothing else running, several times a day, and write the numbers down. If wired is good, the problem is Wi-Fi and the fixes are placement, band, channel and cables. If wired is bad, check your actual package and the master socket, then present the log to your provider against the guaranteed minimum in your contract.
