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mine didn't seem to detect that 11 was available over the air.
hooked the phone up to iTunes was usb and then iTunes prompted me to download and update to iOS 11.

might be worth a try?
 
Yeah, my iPad Air isn't detecting an OTA update but did when I plugged it in to iTunes.
[doublepost=1505852631][/doublepost]After doing that and it still not detecting it, I rebooted the iPad and upon it coming back up, it sees the OTA update now.
 
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