Just before the storm struck last night, ripping off our gates and hot water expansion pipe, we experienced a technology storm of a different sort. It started when my two week old Android tablet seemed to be connected to WiFi but was not connecting to the Internet. A fifteen hour power outage interrupted diagnosis but, when power returned today, both my phone and Annette's Android phone were both showing the same symptoms - connected to WiFi but no Internet access. All other devices (PCs, iPads, Kindle seemed unaffected).
Google searches uncovered an Android bug where IP addresses allocated via DHCP were not being properly recorded in the Android device. Each affected Android device shows it's IP as "Unknown" (Settings/About device/Status).
Although repeated connecting and disconnecting from the network can restore a device to working order, this is hit and miss at best, and frustratingly annoying at worst. The actual answer is to reserve IP addresses on the DHCP server for use by Android devices and to set each Android device using one of these "static" IPs rather than DHCP. Everything else in the network can continue using DHCP but the Android devices each get their own dedicated IP. It's a bit of a pain to set up but once it is done everything works more smoothly and devices connect more quickly.
Hope that helps someone out there with a misbehaving Android.