iPhone 5, iOS 9.0.1, AT&T as my service provider.
If my iPhone is connected to a WiFi network, Mail works just fine. If I’m running on cellular data alone, I cannot retrieve e-mail, and I will sometimes (not always) get the message, “The IMAP server ‘imap.gmail.com’ is not responding. Check your network connection and that you entered the correct information in the ‘Incoming Mail Server’ field.” I’ve done absolutely nothing to my Google account either on the phone or via desktop.
I’ve taken all the usual steps; closed and re-opened Mail, rebooted the phone (simple shut-down/turn on, and whatever they call it when you hold down both buttons simultaneously to shut the phone down), and I’ve tried deleting and re-adding the Google account.
The only thing unusual that has happened is that I was in Italy for the last couple of weeks. I bought an international service plan, including data, and the phone worked fine. Problems began when I turned it on upon landing back in the US (I did use all of my allotted data on the international plan).
The phone seems perfectly functional otherwise; Facebook, Flipboard, Safari, all work fine on cell data. It’s just Mail that’s being problematic.
Any ideas? I’m stumped.