I called tech support. They had me pull the SIM card. After restarting the phone, I've got 4G again (sometimes). they also said that they have been working on the 4G network in my area which may account for the flaky reception.
Speaking of reception, call signal level is quite low at home where my other phones get great reception.
Speaking of reception, call signal level is quite low at home where my other phones get great reception.