If your result is lower than the speed you're paying for, you're not alone, and the cause is usually straightforward to identify.
WiFi vs wired: this is the most common culprit. A wireless connection introduces interference, distance, and signal loss that a direct Ethernet cable doesn't. Before drawing any conclusions from your result, connect your device directly to the router with a cable and run the test again. If the wired result is significantly higher, your broadband line is fine. It's your WiFi that needs attention.
Time of day: broadband speeds slow during peak hours, typically between 7pm and 10pm, when more people are online in your area. This is normal and affects all technologies to some degree, though modern full fibre networks handle congestion better than older copper-based connections. If your speed is consistently low at peak times, your ISP may have a congestion problem on your local network.
Too many devices: every device connected to your network shares the available bandwidth. Smart TVs, games consoles, phones, and tablets can all consume bandwidth in the background through updates and cloud syncing, even when you're not actively using them.
Line quality: if you're on a part-fibre (FTTC) connection, your speed is affected by the length and condition of the copper wire running from your street cabinet to your home. The longer that final stretch of copper, the lower your speed. Switching to a full fibre (FTTP) connection removes this entirely, as fibre runs all the way to your property.
Router age: older routers often can't take full advantage of faster connections. If you've recently upgraded to a faster broadband package, it's worth checking whether your router supports the speeds you're paying for.
Different building materials affect WiFi signals to very different degrees. Standard glass, wood, and fabric cause minimal interference. Brick is a moderate obstacle. Plaster, concrete, and low-emission glass (common in energy-efficient double glazing) are significantly harder for signals to penetrate. Metal is the worst offender and should be avoided entirely. This includes foil-backed plasterboard, which is common in newer builds, and cement board often found in bathrooms. If your home has thick walls or multiple floors, a mesh WiFi system is often the most effective solution.
Most routers broadcast in all directions equally, so placing yours centrally in the home gives the most balanced coverage. Keep it off the floor, away from walls, and clear of other electrical equipment. Avoid cupboards, hallways, or tucking it behind the TV, as these all reduce signal reach significantly. If your router is fixed near your front door by an older master socket, a long Ethernet cable to a more central location (or a WiFi mesh node) can make a noticeable difference.
The most common source of interference is neighbouring WiFi networks competing on the same channel. On the 2.4GHz band, channels 1, 6, and 11 are the least likely to overlap. Most modern routers will select the best channel automatically. Other sources of interference include microwave ovens, cordless phones, baby monitors, and wireless cameras, all of which operate on the same frequencies. Switching affected devices to your router's 5GHz band, which is less congested, often resolves this.
The 2.4GHz band has a longer range and passes through walls more easily, making it better for devices further from the router. The 5GHz band is faster and less congested, making it the better choice for devices in the same room or nearby. Streaming boxes, laptops, and games consoles all benefit from it. Modern WiFi 6 routers handle both bands more efficiently and are worth considering if your current hardware is more than a few years old.
The figures below show the minimum download speed each service recommends per stream. A household watching two simultaneous streams needs roughly double these figures available.
| Service | HD (1080p) | 4K Ultra HD |
|---|---|---|
| BBC iPlayer | 5 Mbps | 25 Mbps † |
| Netflix | 5 Mbps | 15 Mbps |
| Disney+ | 5 Mbps | 25 Mbps |
| Amazon Prime Video | 5 Mbps | 25 Mbps |
| Now TV | 12 Mbps | 30 Mbps ‡ |
| Apple TV+ | 8 Mbps | 25 Mbps |
| YouTube | 5 Mbps | 20 Mbps |
† BBC iPlayer 4K is available for selected titles only
‡ Now TV 4K requires the Ultra Boost add-on
The "headline speed" you see on a deal isn't a maximum; it's an average. Specifically, it reflects the speed that at least 50% of customers on that package can achieve during peak hours, usually between 8pm and 10pm.
Because every home is different, a headline speed is not a guarantee for your specific address. However, if your provider follows Ofcom's voluntary residential broadband speeds code, they must give you a personalised speed estimate and a minimum guaranteed speed before you buy. If your speed drops below that minimum and the provider cannot fix it within 30 days of you reporting it, the code gives you the right to leave your contract without paying early termination charges. During that 30 day window, you must be reasonably available for any engineer visits your provider requires. If you cancel a scheduled visit, the deadline can be extended accordingly.
As of March 2026, the main providers signed up to these protections are BT, EE, NOW Broadband, Plusnet, Sky, TalkTalk, Utility Warehouse, Virgin Media and Zen Internet.
Note: Before reporting a fault, always run a wired speed test using an Ethernet cable to make sure the problem is not simply a weak Wi-Fi signal inside your home. You can also follow the steps in what to do if your speed is lower than expected before contacting your provider.
Providers on this list can also be part of Ofcom's automatic compensation scheme for problems such as a delayed start to a new service, missed engineer appointments, and delayed repair after a total loss of service. More details can be found in our Essential Broadband Switching Guide.
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