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troubleshooting
Why is my broadband slow? How to find the cause
troubleshooting
Slow broadband never picks a good moment. It waits until the film is two minutes from the ending, or the work call has the important person on it, and then it turns everything into a slideshow. The instinct is to blame the provider and reach for the phone. Hold off for two minutes, because the cause is usually findable from the sofa, and knowing which cause you have is the difference between a five-minute fix and a wasted hour on hold to a man called Dave from Retention.
There are really only a handful of reasons broadband runs slow, and they leave different fingerprints. It is your wifi rather than the line. It is the evening rush hour on the network. It is something that changed in the house today. Or it is the line itself, maxed out and never coming back without a new deal. Work out which fingerprint matches and you know exactly what to do.
This is the test that settles most cases, and almost nobody does it first. Plug a laptop straight into the router with an ethernet cable and run a speed test, then unplug and run the same test on wifi in the slow room. If you want the wired test walked through step by step, the full fix list, in order has it.
If the wired result is good and the wifi result is bad, your line is fine and the problem is wifi, which is the most common answer by a distance. That is a placement, band or router issue, and it is fixable without ringing anyone. If both results are slow, including wired in right next to the router, the problem is the line or the provider and you can stop fiddling with wifi. One cable settles an argument that otherwise runs for days.
If mornings are fine and everything falls apart between roughly 6pm and 11pm, you are looking at peak-time congestion. That is the window when the whole street is streaming, gaming and scrolling at once, and the local part of the network gets busy. A dip of 10 to 20% at peak is normal and not worth a complaint. A drop of half or more, night after night, is not normal, and it points at congestion on the provider's side or deliberate throttling.
Throttling is the quiet one. Some providers slow heavy users or busy connections in the evening to keep the network standing, and they are not going to send you a letter about it. The way to catch it is to run a speed test three or four times across a day, morning, afternoon and a couple of times in the evening, and write the numbers down. If the line is healthy at 10am and collapses every night at nine, you have your evidence, and that pattern is exactly what a complaint needs.
A connection that was fine yesterday and crawling today usually has a simple, recent cause. Something in the house is quietly eating the bandwidth: a console downloading a 90GB game update, a laptop installing an update in the background, a phone uploading a holiday's worth of photos. Check what is running before you blame the line.
The other sudden causes are a router that has been on for months and needs a thirty-second reboot, a new device someone just connected or a genuine fault on the line. If your speed has dropped off a cliff and stayed there, it is also worth ruling out an area outage, because no amount of fiddling fixes a fault at the exchange. Our is-my-broadband-down tracker shows whether your provider has a known problem in your area right now.
If the wired test was also slow and it is slow every hour of the day, the line itself is the ceiling and no trick in the house will lift it. This is the honest, unglamorous answer the quick-fix articles skip.
The usual reason is an old part-copper FTTC line, where fibre reaches the street cabinet and tired copper carries it the rest of the way, fading with distance. There is a hard limit to what copper delivers, and you have hit it. The fix is not a setting, it is a faster line, and the type of connection at your address decides what you can move to. Before you do, check what speed you actually need so you upgrade to the right number rather than the biggest one, and whether you are overpaying for the line you already have.
If that is your situation, here is a spread of live deals so you can see what your address can move to, from the cheapest going to the fastest.
Most slow broadband is wifi, and most wifi problems come down to the same short list: move the router into the open and off the floor, use the 5GHz band when you are near it, reboot the thing once a month and stop ten devices fighting over one connection. If the house is big or thick-walled, a mesh system is the real fix, not a cheap extender. We walk through all of it, in order, in how to speed up your broadband, and if you suspect the hardware, start with whether your router is the problem.
Sometimes you have done everything and the line still will not deliver what you pay for. This is where most people get fobbed off, and where knowing one fact changes the call.
Most big providers, BT, Sky, TalkTalk, EE, Plusnet, Vodafone and others, signed Ofcom's voluntary broadband speed code. Under it, they have to give you a minimum guaranteed speed when you join, not the cheery "up to" number, a real floor. If your actual speed drops below that floor and they cannot fix it within 30 days of you reporting it, you have the right to leave penalty-free, including any phone or TV bundled in, and some will put a credit on the bill while they try. Virgin Media is not in the scheme but runs its own version.
So the call has a script. Tell them your measured speed, ideally from several wired tests, tell them it is below your minimum guaranteed speed and ask them to log a fault and start the 30-day clock. Those exact words move the conversation from "have you tried turning it off and on again" to a problem they are obliged to fix or release you from. Be polite, be specific, keep your numbers to hand. The figures do the arguing for you.
If the verdict is that the line simply cannot do better, the only real fix is a different one, and the deals above show what your address can move to.
Because everyone is online at once between about 6pm and 11pm. A 10 to 20% dip at peak is normal. A drop of half or more every evening points at network congestion or throttling, and is worth raising with your provider.
Usually something recent: a big download or update running in the background, a new device, a router that needs rebooting or a fault on the line. Check what is using the connection first, then rule out an area outage.
Possibly, if it is healthy by day and consistently slow in the evening. Run speed tests at several times across a day and note the pattern. A line that only collapses at peak is the classic sign.
Because the line is fine and the wifi is the bottleneck. That means router placement, the wrong band, interference or distance, all fixable at home without contacting your provider.
If your provider signed Ofcom's speed code and your real speed is below your minimum guaranteed level, and they cannot fix it within 30 days, you can usually leave penalty-free and may get a bill credit. Report it, quote your measured speed and ask them to start the clock.
The short version: test wired against wifi to find the bottleneck, watch the clock to spot evening throttling and check what changed if it went slow today. If the line itself is the cap, the only fix is a faster one. Most of the time the answer is sitting in your house, not at the exchange.
Wifi not working splits into two completely different problems. Work out which one you have first, then follow the path that actually fixes it.
No internet at all? Run these five checks in order, from the router to the line to a real ISP outage, and you find the one thing that has actually broken.
If the whole line drops and not just one phone, the fault is your connection, not your wifi. Here is how to tell a re-sync from a router crash from a line fault, and what to say to your ISP.
Most slow broadband is a Wi-Fi problem, not a line problem. Work through the fixes in order, from the 60-second wired test to the point where the only real fix is a faster line.
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