It seems like Samsung has made some changes to the international Exynos Galaxy S9/S9+ and not all T-Mobile 4G LTE bands are supported this year unlike previous Galaxy phones. AT&T is not affected but if you are on T-Mobile, just know you may get stuck on HSPA+ most of the time if you buy the international Exynos Galaxy S9/S9+ models.
Update: The issue has been fully fixed after doing a software update, it was an early bug that is fixed easily with software update. 4G LTE works great now and picking up 4G+ signals also, please disregard this post thanks.
SM-G960F, SM-G960FD, SM-G960F/DS
SM-G965F, SM-G965FD, SM-G965F/DS
A good alternative is any previous Galaxy international models like the Galaxy Note 8, S8, S8 Plus, S7, and S7 Edge, they all support T-Mobile 4G bands fine.
Have a question?Please post all your questions at the new Android Rehab Center at HighOnAndroid Forum, thank you for understanding!
Join the HighOnAndroid VIP Fans List for free help from Max and discounts on Android accessories.