The iPad is main culprit but but both our iphone 4s's also partially toddle off our network from time to time. All IP addresses are governed by the main router which is the DHCP server. The iPad always connects to our network and by and large retains the same IP address. The problem seems to be that whilst the iPad can browse the net and receive emails, notifications etc. it isn't actually visible to any other device on the network unless: WiFi is turned off and on again on the IPad. Or The IP lease is renewed on the iPad. The phones need the same treatment. The giveaway is that the ios device cannot find our Sonos network. The above actions resolve it. I don't have any trouble with our android tablet. Anyone know why my ios devices lose the plot?