Fixed Wireless Internet speed throttling

I have ATT fixed wireless internet. My download speeds should be > 25 mbps. When ATT resets the antenna, my speed jumps to 34.  After a few hours, consistently, my speed drops to 5 mbps. My RSRQ is -17, which means there is no tower congestion. I have used less than 35 gigabytes this month, and my limit is 350. 

Is anyone experiencing throttling down speeds using Fixed Wireless Internet?