The 802.11g wireless standard is sometimes unreliable, can have poor range and seldom achieves its maximum 54Mbps transfer rates, unless you’re very close to the wireless router. When this was the best wireless technology available, Powerline networking kits such as the Zyxel HD Powerline Adapter PLA4205 were a way to guarantee a more reliable network, as Powerline is usually faster, unaffected by range and less likely to suffer connection problems.
These days, wireless networking is much improved. Most new computers and network equipment support the newer 802.11n wireless standard, which in theory can transfer data at up to 300Mbps. It has much better range and is more reliable, so you can quickly download large files to a computer over wireless, play games with fewer disconnections from the server, and stream HD video to a mobile device without it stopping half way through while it waits for more data. Its better performance means Powerline networking equipment such as the Zyxel HD Powerline Adapter PLA4205 is no longer such a necessity. See all Wi-Fi/networking reviews.
Manufacturers such as Zyxel are still developing the technology coming up with new products, such as the Zyxel HD Powerline Adapter PLA4205, which is capable of 500Mbps. Aside from this massive jump in theoretical network performance, the firm has also made some clever tweaks to other aspects of the device. It saves energy by automatically switching itself off after a few minutes if no device is connected to it, and has a built-in quality of service (QOS) manager, to prioritise different types of network traffic in a similar way to most modern routers. See also: Group test: what's the best wireless router?
Initial setup of the Zyxel HD Powerline Adapter PLA4205 couldn’t be simpler. We plugged one adaptor into a power socket near the router and another into a power socket next to a computer, in a different room of the house. Once two pieces of ethernet cable (which comes in the box) connected the adaptors to the router and computer, all three lights came on and the network was ready to go, without any software installation needed.
Zyxel has included some software with the Zyxel HD Powerline Adapter PLA4205, though. It lets you view all the adaptors on your network at a glance, including their Mac addresses, and you can set an encryption password to keep the network secure from other computers, either in your house or the same circuit.
We found a frustrating aspect of the Zyxel HD Powerline Adapter PLA4205 is the positioning of the power connectors at the top rather than the bottom. This makes it unusable if your power sockets run along the skirting boards of the wall, as in the house where we tested the adaptors, so in order to even plug them in we had to move both computer and adaptor to another room.
Although Powerline networking is considered more reliable than wireless, we got vastly different test results depending on the wall sockets the Zyxel HD Powerline Adapter PLA4205 adaptors were plugged into. Initially, with the adaptor connected to a power socket in a room full of computers and gadgets, the best speed we could manage was a measly 42Mbps, far slower than a wireless connection.
This is partly down to electrical interference generated by other appliances in the home. A freezer, television, computer or mobile phone charger can create lots of noise, partly thanks to the use of switch-mode PSUs, which break apart the DC signal into short waves. We unplugged every device we could find, moved the adaptors to different power sockets, and tried again. Performance was improved, with a transfer rate of 93Mbps, but still far from what Zyxel suggests the PLA4205 is capable of.
Our old router was to blame, as we’d forgotten it could only manage a maximum transfer rate of 100Mbps. With that replaced by a model supporting Gigabit ethernet, we slowly plugged our devices back in and tested once more. In a different power socket, we measured a far healthier 314Mbps, although still far from the 500Mbps maximum transfer rate that Zyxel claims, this is significantly better than the real-world performance of any wireless technology we’ve previously tested.