Why your Wi-Fi
is slow
The line is hardly ever the problem. Test with a cable first: if it works well over a cable, the line is fine and the fault is inside your home. From there, the order matters, because each check rules out the next and saves you buying devices you didn't need.
By Ismael Vázquez, founder and technician · Published 5 August 2026
Your provider gets you to the router. From there on, it's up to you
It's the sentence that saves the most arguments, and the one almost nobody is clear about when they call.
When you sign up for a line, what you're buying is the bandwidth that reaches the router. Everything that happens after that (how it's spread around the house, how many devices are pulling on it at once, how many walls it goes through) is your installation, not your provider's.
That's why a 1 Gb line can feel as slow as a bad one: the gigabit is there, but it doesn't reach the back bedroom. And that's why calling your provider on day one usually ends with a remote check that says «the line is fine», which also happens to be true.
The good news is that the order of checks is short and costs nothing. Each step rules out the next, so doing them in order stops you buying a repeater for a channel problem, or changing provider for a placement problem.
Five checks, in this order
Fifteen minutes. No need to buy anything or install anything odd.
Test with a cable
Take a laptop and a network cable and plug it straight into the router. Repeat whatever was failing: the video call, the video, the download. If it works well over the cable, the line is fine and everything that follows makes sense. If it's also bad over the cable, stop here: the problem is the line or the router, and it's time to call your provider with that fact in hand.
Check which network you're connected to
Almost all routers broadcast on two bands: 2.4 GHz and 5 GHz. 5 GHz is much faster and much less crowded; 2.4 GHz reaches further but it's where everyone is. If they appear with different names, connect manually to 5 GHz from the spot where it fails and compare. If they share the same name, the phone decides for itself and sometimes clings to the worse one.
Restart and time it
Switch the router off for thirty seconds and turn it back on. This isn't the fix, it's a test: if it improves for a few hours and then drops again, the router is getting overloaded, and that's the diagnosis. A router that needs a daily restart is asking to be replaced.
Count what's in between
From the router to the spot where it fails, count thick walls and floors. A plasterboard partition barely matters; a load-bearing wall, a concrete floor slab, a built-in wardrobe, a large mirror or underfloor heating with metal mesh do. With two or more serious obstacles, no home router is going to solve it alone.
Disconnect half the devices
Turn off Wi-Fi on everything you're not using and repeat the test. In a home with TVs, consoles, a robot vacuum, cameras, speakers and the family's phones, the sum of idle devices already takes up the channel. If disconnecting improves things a lot, the problem isn't coverage but congestion, and it's fixed differently.
What's usually going on, based on what you notice
It isn't infallible, but it's right most of the time and saves testing blindly.
| What you notice | Most likely cause | Where to start |
|---|---|---|
| Only bad in one room | Obstacles between the router and that area | Move the router or add an intermediate point |
| Bad throughout the house, over cable too | The line or the router | Call your provider with the cable test done |
| Fine during the day, bad in the evening | Channel congested by neighbouring networks | Change channel and use 5 GHz |
| Video calls drop but video streaming works | Low upload or unstable latency | Check the upload speed you're paying for |
| Worse when someone downloads or uploads | Not enough bandwidth or poor sharing | Prioritise traffic on the router or upgrade the line |
| Improves after a restart, then drops again | Overloaded or faulty router | Replace the provider's router |
| One particular device is bad, the rest fine | That device, not the network | Cable it or check its Wi-Fi card |
Four invisible causes
They turn up in real installations more than people imagine, and none of them shows in the coverage bars.
The channel is full of neighbours
In a block of flats there can be twenty networks competing for the same radio space on 2.4 GHz. Your router isn't faulty: it's waiting its turn. You notice it most when everyone gets home, which is why the Wi-Fi «gets worse in the evening» without you having touched anything.
Where the router sits
On top of the fuse box, inside the hall cabinet, on the floor behind a door or next to the boiler. The router ends up where the provider's cable comes in, which is almost never where it should be. Raising it to mid-height and taking it out of the cabinet is free, and sometimes that's all it takes.
One slow device holds everyone up
Wi-Fi is a shared turn. An old device that only speaks 2.4 GHz and at low speed holds its turn much longer than it should, and the others wait. A printer, an old camera or a speaker can be slowing down the whole network.
Two networks switched on at once
The classic case of someone who sets up mesh or a repeater and also leaves the provider's router Wi-Fi running under another name. Devices stay stuck to the worse of the two and won't let go on their own. If you replace the router's Wi-Fi, you have to switch the router's own off.
The sign that it's time to call
There's a point where carrying on testing costs more time than it's worth, and it's best to recognise it.
When it's also bad over a cable. Then the Wi-Fi is innocent. With that test done, the conversation with your provider changes tone and usually ends in a technician visit instead of «restart the router».
When the drop-outs keep a schedule. If it cuts out at the same time every day, or whenever a motor, a lift or the air conditioning starts, it's electrical interference or predictable congestion. That gets measured, not guessed.
When you've done everything above and nothing has changed. That usually means it isn't power that's missing but distribution: the Wi-Fi isn't reaching the places where it's used. That's solved by measuring real coverage and putting the access points where they belong, which is almost never where you'd put them by eye. If that's your situation, the next step is knowing how many nodes you need and where.
And if you'd rather not keep testing: we come over, measure the coverage in your home or premises and tell you what's going on, what can be fixed by moving what you already have and what needs something new. The diagnosis is free, and quite often it's solved without buying anything.
What people usually ask
How do I know whether it's my provider's fault or mine?+
With a network cable, repeating the test at the moment you actually notice the problem, not at some other random time. Connect a laptop directly to the router with a cable and do exactly what was failing: the video call, the download, the video. If everything works fine over the cable, the line is working properly and the problem lies between the router and the device you're using, not in the connection to the building or the contract. If it also fails over the cable, especially at the same time of day or repeatedly, then there's reason to call your provider, and you call with objective data in hand rather than a feeling, which makes quite a difference to how you're dealt with at the other end. One important nuance: if the fault is intermittent, test over the cable several times at different moments, because a single good attempt doesn't rule out a line problem that only appears at certain times of day.
I have 1 Gb fibre and it's slow. How can that be?+
Because the contract measures the bandwidth that reaches the router, not what comes out of it over Wi-Fi, and that difference is what people don't expect. It doesn't matter that it's 1 Gb: as soon as the signal leaves the router it has to be shared among all the connected devices, cross the walls of the house, compete with neighbours' networks using the same radio space and adjust to the speed of the slowest device you have switched on at that moment. No home Wi-Fi delivers over the air the same speed that arrives over a cable, and the further from the router and the more obstacles in between, the more you notice it. That's why the right diagnosis isn't «my provider is ripping me off», but separating the two parts: check with a cable that the gigabit reaches the router, and from there treat distribution around the house as a separate problem, fixed through the internal setup, not by changing provider.
Should I connect to the 2.4 GHz or the 5 GHz network?+
To 5 GHz whenever it reaches you with some margin, because it's faster and much less crowded than 2.4 GHz, which practically every neighbour in the building shares, along with quite a few household devices. The exception is when you're far from the router or have several walls in between: there, 5 GHz can arrive so weak that 2.4 GHz, though slower, gives a more stable result, because it gets through obstacles better. If your router broadcasts both bands under the same network name, the phone chooses on its own according to criteria that don't always match what suits you, and sometimes stays stuck on the worse band even close to the router. In that case it's worth splitting the network names, even temporarily, to check which works better at each spot in the house before deciding whether to keep them combined or separate.
Does restarting the router help at all?+
It helps as a diagnostic test, not as a permanent fix, and the key is what happens after the restart. If after switching it off and on the connection clearly improves for several hours and then gradually degrades again, it's a fairly clear sign that the router is getting overloaded with use, whether through memory, heat or the number of connected devices, and that pattern is useful data for deciding whether it's time to replace it. If, on the other hand, restarting changes nothing, the problem probably isn't the router but coverage, the channel or a particular device, and it's worth looking there instead of carrying on restarting for no reason. What isn't normal is needing to restart it every day to keep it going: that's not maintenance, it's a router telling you it can no longer cope with what you're asking of it, and it deserves a check or a replacement rather than living with the habit.
Will a repeater fix slow Wi-Fi?+
Hardly ever, and it's one of the purchases people most regret. A classic repeater receives the signal over Wi-Fi and rebroadcasts it over Wi-Fi, so each hop costs a good part of the available speed, and it also creates a second network with its own name that devices latch on to even when it gives worse results than the original, without anyone understanding why the phone «has been worse since we put the repeater in». A well-placed mesh system is a different matter: the nodes talk to each other over a dedicated channel instead of competing for the same airtime the devices use, so it distributes the signal without penalising speed as much. But neither a repeater nor mesh fixes anything if the real problem isn't distribution but channel congestion, the line or a particular device: in those cases adding another node just adds another network competing for the same space, without touching the real cause.
Why does it work well in the living room and badly in the bedroom?+
Because between the two spots there are obstacles that weaken the signal far more than the straight-line distance, and that's what surprises people most when they check. Ten metres of clear hallway barely reduces the signal; a single load-bearing wall, a concrete floor slab between storeys, a built-in wardrobe full of clothes or a large full-length mirror can reduce it more than crossing the whole house along an open corridor. The angle counts too: the signal gets through a wall better head-on than diagonally, because diagonally it travels through more thickness of material even if the distance on the plan looks short. That's why the solution is almost never «a more powerful router», which still hits the same obstacle, but changing the point the signal is broadcast from, so that the path to the problem room crosses fewer serious obstacles or crosses them head-on rather than diagonally.
Can a single device make it slow?+
Yes, and it's one of the least suspected causes because the slow device isn't the one being used at the time. Wi-Fi is a shared turn: only one device transmits at a time on each band, so an old one that only speaks 2.4 GHz and at low speed holds its turn far longer than it should need to send the same amount of data, and meanwhile the rest wait, even if they all have an excellent signal. The usual suspects are devices almost nobody looks at: an old printer, a low-end security camera, a cheap smart speaker or smart bulb. To identify the culprit, turn off Wi-Fi on everything you're not using at that moment and repeat the test that was failing; if it improves noticeably, reconnect the devices one by one until you find the one that makes it worse again, and that's the unit worth cabling or replacing.
When should I call straight away?+
When the fault over a cable is just as bad as over Wi-Fi: then Wi-Fi is ruled out completely and the problem is the line or the provider's router. Also when the drop-outs follow a clear time pattern, for example always at the same time or whenever a particular appliance starts up, because that usually points to electrical interference or predictable congestion, something worth measuring rather than continuing to test blindly. And when you've already done the checks on band, channel and connected devices and the result is just as bad: at that point carrying on by yourself starts to cost more time than it's worth, and what's usually missing is a coverage diagnosis based on real data, not another round of home tests. When you call or book a visit, bring the result of the cable test and, if you have it, the time the fault happens: with that, the technician starts halfway there.
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