Update: Based on reports, the issue has arisen from a network verification process baked into the software, wherein the OS attempts to load a dummy page on Apple.com to detect if a users is connected to a paywalled network. Unfortunately, however, the verification page seems to lead to a 404 error, resulting in an inability to connect to Wi-Fi for many users.
Apple has corrected the problem by updating the page to remove the 404 error. Users should have no further issues connecting. (Via: The Verge)
So it seems that there may be a major issue with Apple’s newly released iOS 6 when it comes to Wi-Fi. Several users across Twitter and on Apple’s discussion board are reporting that after updating their device to iOS 6 the Wi-Fi is now greyed out. The issue seems to be affecting both iPads and iPhones but not everyone.
There are multiple reports of individuals in the same home updating devices and one person has the issue and the other doesn’t (two 4S’s get upgraded, one works and one doesn’t).
Update: Some suggested fixes are coming out from folks, though they seem to be hit or miss for different users. Here’s one:
iOS 6 WIFI FIX FIX: Settings:Wi-Fi > (Network…) > “Blue Circle Arrow” Scroll down to the bottom of the screen and set HTTP Proxy to Auto
Let us know if it works for you and stay tuned to this page for more info as it becomes available.