iOS 16.5.1 issues

I have 16.5.1(a) but my iPad Mini 6 cannot download 16.5.1(c) as it gives me an error message that a download requires a wi-fi connection. I also cannot backup the same iPad receiving a similar error message. For the record, I have a screaming wi-if signal. I spent over an hour with AppleCare last night and they were not able to address the issue and have referred me for a technical support appointment. As an experiment, I wiped an older iPad edition 4 with the same issues and reinstalled everything from scratch. It did update the IOS to 16.5.1(c) but would not do so without requesting access to cellular data. I checked yes even though this particular iPad had no such plan and it did download (the same issue cropped up with apps). The old iPad still will not backup. Any ideas?

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