Hi all, I have had a strange problem with my AT@T mobile hotspot on my iPhone 4. Basically the iPhone does not show up on other devices as a hotspot, even when turned on. Even when turned on, then off, then back on. Even when I turn it off, reboot the iPhone and then turn it back on. Neither my iPad nor my Macbook Air can see the hotspot. But this only happens maybe 10% of the time. The rest of the time my iPad and MBA see and connect right up to the iPhone when I turn on Hotspot. And when it happens, the problem seems to cure itself after an hour or so. It happened in a restaurant today. I rebooted the phone twice and the MBA once. Still it never showed up. I got home and tried it a half hour later and viola, it shows right up on the list of networks. I don't get it.