Each test is performed at least five times, and the result averaged.
The DSL-2740B appears to be quite sensitive to interference from solid and metallic barriers. Throughput remained at around 20Mbps from five metres to 25 metres, after which it fell away to 5Mbps after 55 metres.
If you intend to connect to ADSL2+ over a wireless router and are one of the lucky ones that can achieve a speed between 21Mbps and 24Mbps, the D-Link DSL-2740B won't be able to deliver the full speed to wireless clients. This isn't a show stopper as a large majority of homes are unlikely to hit this speed or even have the option available, but it's something to keep in mind.
Wireless performance was a little erratic — we had better performance from the smaller, tested at the same time.
D-Link provides a generous three-year warranty.