I bought a China version of K30 5G Racing and unlocked bootloader and everything then flashed to eu rom, everything works pretty well EXCEPT the mobile data connection. When I am still in CN version, I can use 4g anytime and still get good high speed connection even when I'm inside the house. But now using eu rom, I can only get 3g as highest stable connection, not really stable and very slow. I already tried everything such as locking it to LTE only using engr. mode or any apn but has no result. The thing is I can get 4g connection but after 2 seconds, it will get 4g bars then became 0 bars of 4g then becomes 3g again which is only the best option. 3g! I want to know if there are bands that have been romoved from the CN rom to stop suffering from this type of problem.