ADSL and VDSL2 use the copper telephone network. Available speed decreases with the distance between your home and the local exchange. An ADSL or VDSL speed test shows the speed actually available on your line.
ADSL vs VDSL: what is the difference?
ADSL2+ usually peaks between 8 and 20 Mbps download, with a lower upload. VDSL2, available on short lines, can reach 30 to 100 Mbps. The closer you are to the exchange, the better your chances of a high speed.
| Technology | Typical download | Typical upload | Condition |
|---|---|---|---|
| ADSL 2+ | 8 to 20 Mbps | 0.8 to 1.5 Mbps | Standard copper line |
| VDSL2 | 30 to 100 Mbps | 8 to 20 Mbps | Home close to the exchange |
| Short VDSL2 | 80 to 100 Mbps | 15 to 25 Mbps | Short, high-quality line |
Why is your ADSL speed lower than advertised?
Distance to the exchange
Every metre of copper attenuates the signal. Beyond 2 or 3 km, speed drops sharply. This is the main reason two neighbours can have very different speeds.
Line quality
A damaged cable, a faulty ADSL filter or an oxidised socket degrade the signal. Test with another cable and a new filter.
Wi-Fi and devices
As with fiber, a Wi-Fi test can underestimate line speed. Connect a computer over Ethernet to isolate the local network.
Congestion and the test server
Speed can vary with time of day and the test server. Run the test at different times.
How to test your ADSL or VDSL speed
- Disconnect other devices from the network.
- Use an Ethernet cable between the computer and the router.
- Close applications that use bandwidth.
- Run the test several times at different hours.
- Compare the result with the estimated speed of your plan.
Good to know: your ISP must tell you the estimated speed of your line. If the measured speed is consistently much lower, you can ask for a diagnostic.
How to improve ADSL or VDSL speed
Check the wiring, replace filters, plug the router into the main socket and keep it away from electrical interference. If your line supports it, ask for VDSL2 or fiber. In areas without fiber, a 4G/5G router can be an alternative.
Frequently asked questions
What ADSL speed can I expect?
ADSL2+ usually delivers 8 to 20 Mbps depending on distance to the exchange and line quality. VDSL2 can go much higher on short lines.
Why does my ADSL speed drop in the evening?
Peak-hour network congestion can reduce speed. Testing at different times helps distinguish a line problem from temporary congestion.
Is VDSL2 available everywhere?
No. VDSL2 depends on distance to the exchange and your ISP equipment. Check eligibility with your provider.
Do I need an ADSL filter?
Yes, a filter is required on every telephone socket in use, unless your router has a built-in filter. A faulty filter can reduce speed.
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