Hi I have a galaxy note 9. For the first 3 or 4 months I had this phone I had 4g LTE coverage. Then it randomly dropped to 3g about a month ago and won't change. Now today my one has gone into roaming and won't come out of it. I tried dialing the ##72786# but it's still stuck in roaming. How do I get it out of roaming and then get back my 4g coverage?