Does the phone give you LTE speed? If so, does it matter what the letters spell out? (If it were my phone, and said "LTE Unavailable" and still worked at LTE speed, I'd just ignore it.)
If it doesn't give you LTE speeds, make sure the phone is the right one for LTE for your carrier. Mixing phones and carriers can give you a phone that doesn't have a radio for the LTE band your carrier uses.