DHP-300

Sharing large files or a high-speed ADSL2+ connection over a wireless network can sometimes be a frustrating experience if the signal is too slow from the access point to the client devices. But while wireless has been touted as the best solution against messy cable installations, a better option might be an Ethernet-over-power-line adapter, especially for large dwellings. Note: we said 'might'.

D-Link's DHP-300 adapter performs the task that its name implies: it moves Ethernet data across power cables to any outlet in the house or office that's on the same power circuit. At least two adapters are required (or you can buy the DHP-301 kit, which comes with two adapters): one local adapter, which needs to be plugged into your router, and at least one remote adapter, which needs to be attached to the device you wish to connect to -- it can be another computer or a streaming device for music and video.

The DHP-300 can enable encryption for data that travels across the electrical network, while an administrator password can also be implemented to ensure that encryption can't be changed by unauthorised persons. However, the setup process is not helped by the cryptic labelling of the adapters in the configuration utility.

The remote adapter is called PLC and the local adapter is called ETH. When applying encryption and password settings, the remote adapter needs to be configured first, then the local one; there's really no way to tell which adapter is which unless you read the manual. D-Link needs to apply clearer labels to this utility to make it more user-friendly. Another quibble with the utility is that it doesn't report back on line speed.

A speed of 200Mbps is quoted for the DHP-300, but this is a theoretical figure that doesn't take into account factors such as encryption, line quality and length, as well as any other high-power devices on the electrical circuit, such as fridges and air-conditioners. Dwellings with poor wiring installations might not realise fast speeds when DHP-300 adapters are installed, and other devices that can cause the adapters to not work properly are power strips and surge protectors. However, the adapters aren't designed in a way that makes them easy to plug into a wall outlet, so a large power strip is a necessity.

We tested two DHP-300 adapters using a power strip with surge protection, and we didn't experience any problems. Using electrical outlets on the same physical circuit, we were able to transfer data from our local device to our remote one at a rate of 2.67MBps. A best-case scenario test, with both adapters plugged into the same power board, merely centimetres from each other, recorded a rate of 3.53MBps.

The rates we achieved in our test environment aren't as good as what we've achieved with a draft-n based wireless router (such as D-Link's DIR-615), but they're better than what we'd get with an 802.11g-based router. Furthermore, the results are slightly better than what we achieved with Netgear's Powerline HD Ethernet Adapters (HDXB101).

There is potential for users in dwellings with perfect wiring and line conditions to attain higher-than-wireless transfer speeds over a comparable distance, but there's no guarantee. Nevertheless, if your wireless installation is giving you grief, a couple of DHP-300 adapters might solve your problems, but won't give you the ubiquitous multi-device coverage of a wireless network. You'll have to purchase an adapter for every device that you want to connect to your network; up to 16 DHP-300 adapters can be installed on one network. Each one will consume about 39W of electricity.