Since last several days, LTE is not working. Does any one have any idea to solve this problem?

same here, what I read is that they are still working on it

LTE has been down for everyone(I think?) since December 8th. Rumors say it should be fixed sometime this week.

Keep on waiting...

Wait a little bit more...

Switching to another provider is the only way to fix it for now... or keep waiting. It's been couple weeks now that LTE is down.

Patience is a virtue......hurry up dammit!

You got Fizzted

It has not worked in well over a week now. There is no ETA for service restoration.

LTE functionality was restored today. I can't say 100% for sure, but it seemed to coincide with the update to iOS 12.1.2.