My own progress report:
This only cropped up for me 2 days ago. The switch was visible but greyed out and unselectable.
I went through all the recommended steps:
- reset network settings
- reset all settings
- restored iphone to factory settings
- restored iphone to factory settings and restored from backup
- tried http proxy change
- cleared safari cache, history, cookies
- turned cellular off and turned back on
- sat on phone with apple support for a while we went through a checklist that included much of the above
- TOOK IPHONE 4S TO APPLE STORE AND GOT A REPLACEMENT PIECE OF HARDWARE
I thought the last step fixed things, and it worked, for 24 hours.
Then tonight, i went to plug in the phone for the night noticed the greyed out WIFI button was back.
So, I checked my Airport Express settings. Everything was up to date, and as close to factory defaults as they come. I switched the channel from Auto to, in my case, 3.
WIFI immediately showed up on the iPhone.
A possible artifact of N channel congestion and not smart AP channel management...?
I dunno. But we'll see how long this lasts.
[I can't believe Apple stores are just replacing phones in these cases and that a patch for this problem, which as been existant since at least September, is neither imminent nor informing AppleCare support practices. Pretty disappointed in Apple right now.]
