new 5g gateway won't connect to the internet

Took me 4 Attempts to get a Gateway 5G that worked longer than a week.  Meaning it took nearly 5 weeks to get connected for more than a few days.  Bring it back to the store, hook up new one, fails in a week.  Took it back to the store.  Worked a few days.  Took back to the store.  Arranged with TMobile to send me their very first 5G model after 4 hours  phone calls.  Received it at my home and bingo.  The tower was directly across the street in a Chruch Parking Lot.  Maybe 300 feet from me.  Then /I moved 3 miles and the closes tower was 2 miles away and service would be good but not great then weak then back to good several times an hour.  In the evenings some times it would not hardly connect until 10pm or so.