bit of a update
if you set the router to use auto channel width(20MHz+40MHz) the ipad and iphone the latest ones don't like this router connected to the 2.4Ghz because apple doesn't use the 40MHz only 20MHz on these devices! they keep dropping out from the wireless signal and causing other devices to drop out (unidentified network) so when you set the router to use just 20MHz i loose signal and bandwidth down to 150Mbps affecting my other devices. so what i have done is set the 5Ghz band up for the apple devices and it has cured the problem(for now at least).
iOS and OS X: Recommended settings for Wi-Fi routers and access points