Issue 3G - 4G don't roam correctly
I was in a shopping center with a bad 4G reception when device change to a 3G antenna. After, when I exit shopping center and go to another place with a very good 4G reception device doesn't change automatically to 4G. Restarting or turning off device don't solved the issue. I had to go to network options and change to 2G/3G option and after 2G/3G/4G again to solve!
(Test performed with a S9+ on the side, perfect reception)