We have a brand new Airport Extreme (Simultaneous Dual-Band II). This replaced an older model that worked perfectly until it died. This new machine will drop the connection for all connected devices, when any new machine connects to the network. Connected devices include MacBook Pros, iPads and iPhones. It happens about 50% of the time a device connects. When it does happen, our network name just disappears from the list of available networks. If you try and connect manually, you get a timeout. Left to its own devices, it will eventually reconnect after a few minutes and apart from the annoying reconnection delay, it loses the VPN connection we all have on the laptops. Frustrating to say the least. I have updated the firmware and of course restarted the Airport many times. Is this fixable or should I return the unit for replacement? Thanks for any suggestions.