This morning my iPhone 5 was unable to join my home WiFi network. My home computer, iPad 2 and my old iPhone 4 (now my wife’s “iPod Touch”) worked fine. I tried the normal troubleshooting on the iPhone. I rebooted, forgot the network, reset network settings, and still no connection. Then I decided to log into the router. I could not. A simple reboot of my home router, a Linksys E1000 fixed the issue.
The first step in troubleshooting “Unable to Join Network” – reboot the router.