You pay for a fast package, the advert promised big numbers, and yet the speed test keeps showing a fraction of it. It is one of the most common and most frustrating broadband complaints, and the honest answer is usually a mix of a few things, most of which are fixable once you know where to look. Here is why you might not be getting the speed you pay for, and how to tell which cause is yours.
Advertised speed is not a promise to your desk
First, a reality check on the numbers. Broadband is sold on “up to” or average speeds measured in ideal conditions, not a guarantee of what lands on your laptop over Wi-Fi at 3pm. What you can hold a provider to is the guaranteed minimum in your contract, which is usually well below the headline figure. So part of the gap is normal, but a big gap, especially on a cable, is worth chasing.
The usual causes
| Cause | The sign | The fix |
|---|---|---|
| It is the Wi-Fi, not the line | Fast on a cable, slow on Wi-Fi | Improve Wi-Fi, or test on a cable |
| Measuring over Wi-Fi or an old device | One device much slower than others | Test wired, on a modern device |
| Contention at peak times | Slow only at busy times of day | A business line with lower contention |
| Old router or internal wiring | Consistently low, even wired | Newer router, check the wiring |
| Background usage | Drops when backups or CCTV run | Prioritise, or more upload |
| A genuine line fault | Sudden drop, high ping, dropouts | Report it with evidence |
How to check properly
- Test on a cable. Plug a laptop straight into the router. This removes Wi-Fi from the picture and tells you whether the line or the wireless is the problem.
- Use a sensible test. Run a reputable speed test, ideally more than once, and avoid testing while big downloads or backups are running.
- Try another device. If only one machine is slow, the device is the issue, not the line.
- Test at different times. Slow only at peak suggests contention; slow all day points at the line, the router or the wiring.
The single most useful step is the wired test. It splits the question in two in thirty seconds: a healthy wired speed means your line is fine and the problem is Wi-Fi; a low wired speed means it is the line, the router or the wiring, and worth reporting.
When it is a real fault
If you are well below your guaranteed minimum on a cable, or you are seeing sudden drops, high ping or dropouts, that is a fault worth raising, not just living with. Gather a few details first so it gets fixed quickly, using our fault checklist, and if you are not sure whether it is the line or the Wi-Fi, run the quick Wi-Fi versus internet test first.
Frequently asked questions
Why is my broadband slower than advertised?
Advertised speeds are “up to” or average figures measured in ideal conditions, not a guarantee at your desk. Real speed is reduced by Wi-Fi, old devices, contention at peak times, internal wiring and background usage. A wired test tells you how much of the gap is the line versus your Wi-Fi.
What speed should I actually be getting?
Check your contract’s guaranteed minimum, which is the figure you can hold your provider to. On a cable you should comfortably beat that. If you are below it wired, it is worth reporting as a fault.
Does Wi-Fi reduce my broadband speed?
Often significantly. Distance, walls, interference and old devices all cut the speed you actually see over Wi-Fi, even when the line is delivering full speed to the router. That is why testing on a cable matters.
Why is my broadband slow only at peak times?
That is usually contention, your connection being shared with others at the busiest times. A business-grade line with lower contention, or a dedicated leased line, holds its speed when a shared line sags.
How Synergy Max helps
We cut through the guesswork: we check whether the shortfall is the line or your Wi-Fi, look at contention, the router and the wiring, and raise a genuine line fault with evidence if there is one. If the real issue is a contended or undersized connection, we will right-size it, see our guides to how much bandwidth you need and business versus home broadband. Explore our business broadband and we will make sure you get the speed you are paying for.