Why did my Nokia gateway stop receiving 5G signals?

My Nokia home internet gateway has been working well since I got it last year. I usually get 2 bars of 4G signal and 2-3 bars of 5G signal. And my speeds vary throughout the day, but are generally around 50-75mbit during peak hours and over 100mbit during off-peak hours.

This week my Nokia gateway stopped receiving any 5G signal. I've rebooted many times, but it doesn't connect to any 5G towers. As a result, my speeds have fallen dramatically. My peak speeds are now in the single digits and my off-peak speeds are usually around 25mbit.

My gateway hasn't moved. I spent days finding the perfect location that provided the highest SNR for 5G. Is there something wrong with my gateway? How do I get my 5G signal back?