iPad (3rd gen) loses cellular connection (ATT) every 20 - 25 seconds
My iPad (3rd gen, iOS 8.2) works fine on WiFi, but its cellular connection cycles between "searching" and a strong signal (5 dots) every 20 to 25 seconds. It's been doing it for a week now, at several different locations. I've restarted the iPad, removed and reinserted the SIM chip, and reset network settings. None of those helped. Any ideas on what I should do next?
iPad, iOS 8.2, AT&T cellular