Will using my own router resolve some issues with the T-mobile router?

I am fed up with T-Mobile home 5g internet..2 different gateways the round grey one saying connected with no internet...now I have the square black one saying connected unable to provide internet.....I spent all weekend on the phone in the store back on phone for hour or so doing every test they could think of no answers..not it's going to the engineer's....one last chance and I'm finding someone else