Can you fish an antenna outside your window, and have a few hundred dollars to spare? You might get better signal with a booster. I use one from surecall on my car and it fills in the gaps in coverage well. Not sure if I get 5g or not, but I get adequate cell service. I think they have ones for the home, ideally with a directional antenna and mast. At that point, you should have great 5g, but your mileage may vary.