Forum members report that after upgrading to iOS 6, both the legacy iPhone 4S and new iPad are experiencing disabled Wi-Fi connectivity that leaves the option to connect "grayed out." The issue appears to be affecting Bluetooth capabilities as well, with some users claiming their units are unable to pair or even recognize other devices, and show the spinning "search wheel" indefinitely.
Another set of users have the ability to turn Wi-Fi on in Settings, but are unable to connect to their local network.
Both the nature and extent of the purported iOS 6 complications are unknown, including whether the two issues are related, though many affected users who have contacted Apple say the company is aware of the problems.
A number of fixes have been suggested, including a hard reset and reinstallation of iOS 6, but the most effective seems to be resetting Network Settings and changing the HTTP Proxy to "Auto."
For those who are seeing a completely grayed out Wi-Fi toggle switch in Settings, a few users have had luck with downgrading to iOS 5.1, suggesting the issue is exclusive to iOS 6. Other members have successfully exchanged their affected iPhones for new hardware after demonstrating the grayed out Wi-Fi option to staff at the Apple Store Genius Bar, though it is unclear if handset replacement is the usual course of action.
When iOS 6 was released on Sept. 19, a number of early adopters suffered from Wi-Fi issues, however Apple was able to trace the problem back to a downed verification page which was quickly repaired.