There is herein disclosed a method of measuring the performance of a first communication channel at a first access point in a WLAN, in which the first access point is associated to a client device so that the first access point can send data to, and/or receive data from, the client device on a second communication channel, the method including disassociating the first access point to the client device and associating a second access point to the client device; switching the working channel of the first access point from the second communication channel to the first communication channel; and making one or more performance measurements in respect of the first communication channel at the first access point.