High-Speed Internet Gateway will not lock to 5G speeds (5G21)

Got the Nokia gateway last Wed (May 5). Initially only got 2 of 5 bar signal strength, in metro area that T Mobile said has 5G available (I understand how that goes, "not necessarily where your exact location is" ) Still, highly motivated to get away from years of plunking down 3 figure monthly fee for landline TV and internet (cable co.). Having some skills at using web GUI's I opened the one for this Nokia, noticed the "wireless" menu under "network" on left pulldown menu, opened each radio (2.5GHz and 5 GHz), I decided to turn off all of those (had to do it on each WiFi sub-SSID, 12 in total-- attention T-Mobile, y'all need to do some serious web page re-design to simplify that! 😉 ) since I have my own established SSID's, and connected the gateway via ethernet to WAN on my home router. VOILA, it immediately got 3 of 5 bars, rechecked "speed test" on Google and it gets solid 40 MB/sec down, 9 MB/sec up, ping in low 30's ms. I'm not a "gamer" so ping time isn't a great concern until it gets over 50-- since Thursday, still solid on 3 bars, band 12 (I realize that isn't 5G, so if there's a disappointment, it's that so far).