Rogue access point connection blocking method, access point device and the wireless lan system

A wireless local area network system includes one or more access points connected to a wired network which is part of the system. To prevent wireless terminals from communicating with a rogue access point that is not connected to the wired network, a legitimate access point detects the rogue access point, determines its beacon signal period, and sets a timer to generate timings at which the rogue access point is expected to transmit the beacon signals. At each of these timings, the legitimate access point creates and transmits interfering data that interfere with the rogue access point's beacon signals.