ZyXEL PLA4205 Powerline Adapter review

Dave Mitchell Read more February 8, 2012

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£68

Price when reviewed

Powerline adapters are great for cable-free networking, but their mediocre speeds have always put off businesses. Enter the ZyXEL PLA4205 Powerline Adapter, which claims a throughput of 500Mbits/sec.

This palm-sized package has a Gigabit port and three LED indicators for power, Powerline connection quality and activity. An encryption button can be used to manually set up network connections between adapters.

ZyXEL has also gone green. If an adapter spots that an Ethernet connection isn’t present, it drops down to a 1W low-power mode.

With a twin pack, we found them easy to set up. We’ve always found performance drops as cable distance increases, so we started with them plugged into the same power strip, although their width blocks access to adjacent sockets.

A Windows utility is used to assign names to groups of adapters, so they can share the same power cabling but be on separate networks. Different priorities can also be applied to adapters for basic traffic QoS.

We connected a dual-Xeon X5560-equipped Windows system to one adapter and linked the other to our network. At default settings a link was established immediately, and the test system had full network access.

For tests we used a Synology RS3411xs NAS appliance, and started with a direct Gigabit link. Iometer reported a 112MB/sec raw read rate for a mapped share, and copying a 2.52GB video clip returned 103MB/sec.

With the ZyXEL adapters in position, Iometer now reported 26.5MB/sec and the file copy returned 25.5MB/sec. This equates to around 212Mbits/sec, which is less than half the claimed speeds.

We increased the power cable distance to 25 metres and, with a green light for link quality, our file copy now returned only 7MB/sec. During the tests, ZyXEL’s utility was showing receive and transmit speeds as high as 381Mbits/sec.

We’ve no doubt the PLA4205 is priced well and easy to use, but in our experience the claimed performance speeds are little more than fantasy.