Edimax speed issues

[chorlton2080]

Hello folks

I have four Edimax EW-7811un USB WiFi adapters in use on my Pi's. All are installed with Raspian with no changes to the default wireless config.

When connected to laptops and using 'iperf', I regularly see LAN transfer rates of ca. 20Mbit/s. Great, but not spectacular given I'm using an Asus Dark Knight router.

On the Pi's however, in the same physical location, I'm never getting above 0.2Mbit/sec: that is whether I'm testing between Pi's or between laptop and Pi. This is also evidenced by slow apt-get update performance, which I'm confident now is more to do with the LAN than the WAN.

Power management is turned off and the link speed is stated as 72Mbit/sec according to iwconfig.

I'm using Wireless G mode for all devices.

Can anyone offer assistance?