Windows laptop can't find T-Mobile Home Internet network... but all other devices can

Not a computer geek, electronic hobbyist 60+ years, electronic service rep for a year--all this to give background.  I believe Anthony C's post above was absolutely correct.  Set up Gateway, connected 2 smart TVs, year old Lenovo laptop (Win 11), 20 yr old Toshiba laptop (Win 7), old HP desktop (Win 7), two smartphones to Gateway with no trouble--WiFi listed on all 7 devices.  All devices have been on our Century Link WiFi router.  Could not get 9 yr old Lenovo 11S to find Gateway.  Traveled with this laptop for business/pleasure, never problem connecting before.  Spent between 2-3 hours with TM tech assist, yesterday, no luck.  Came across post about transmission channels, logged into CL router, was transmitting on Channel 6 (not set on Auto).  Changed TM Gateway to channel 6 (from auto), laptop display would not list Gateway (I had deleted the CL router already).  I then did what Anthony C recommended, changing the Transmission mode from (Auto) AX/G to N/G and immediately the Gateway appeared.  I can't explain how a 20 year old laptop and a desktop, both running Win 7 can identify the Gateway Auto (AX/G) and this Lenovo couldn't, other than a Network Adapter quirk.  I probably spent 4 hours or more of my own time updating the adapter driver, searching the web, another few hours with Tech Support.  My suggestion:  Do as Anthony C suggested--log in as administrator and try changing the transmission protocol.  TMobile Tech support needs to get with the program.  Thank you, Anthony!!