Fluctuating speeds. Stream not consistent

Why does the speed fluctuate tonight 300 and then 10 and then a 200 and 0 and then like 350 and then like 20. No matter what setting I put it on low high or it keeps on fluctuating between high and low numbers. I’m connected to it through hb3 using Wi-Fi to my router. Is this just a quirk? I know that ethernet is generally better and location is also better when it’s closer. But does anyone else experience this even in the best of environments?