my other phone was Xiaomi Mi Note 2. I know for sure I saw 4G+ on that phone before. Given the Note8 is capable of LTE advanced, so I would expect to see 4G+.
if you check the specs here
https://www.gsmarena.com/samsung_galaxy_note8-8505.php
it shows it supports LTE-A (which stands for advanced)
4G bands LTE band 1(2100), 2(1900), 3(1800), 4(1700/2100), 5(850), 7(2600), 8(900), 12(700), 13(700), 17(700), 18(800), 19(800), 20(800), 25(1900), 26(850), 28(700), 32(1500), 38(2600), 39(1900), 40(2300), 41(2500), 66(1700/2100)
Speed HSPA 42.2/5.76 Mbps, LTE-A (5CA) Cat16 1024/150 Mbps
Are you in California with Tmobile as well?
Anyone else in this forum?