I had service with Sprint, no service with TMobile and ATT tower close. Why no coverage?

When I had sprint, I had service at my home.   All of a sudden, now my service is gone and the coverage map is showing my area with "no coverage" and no partner service.   What is going on? 

My friend with AT&T has full 5g and that tower is a mile away.  If Tmobile shares towers, and one is close, why don't I have an coverage at all?   Will buying a wifi extender help?   

Any input would be great.  Thanks!