It means more data is comming into the modem then it can handle, causing resends, MSFS doesn’t like that at all.
If your netgear router supports is, you can go trim it in there until you make the BB go down or away altogether.
The other thing you can do is find a broadcom chipset cable modem, and replace the old one with the new one and that should fix it as well. You’ll have to research well, because its not something that seems to be advertised on the modem boxes when you looking for one.
It seems that there are 2 predominante chipsets Puma and Broadcom, and the Puma based ones are the ones the cant handle the throughput of the connection and causes resends. And the resends cause MSFS to run / look like cr**.
If you router supports it, it should be under the QOS settings, should be 2 sliders. The way I did it was to start at my advertised speed 100mbps and then run the test. If its bad slide the slider back to 90 and run the test. Rinse and repeat until you get less then 100ms of BB. Ive adjusted mine to run around 70mbps and I get no BB on the site at all anymore. Of course that means that my 120mbps connection is really only 70mbps so it does tick me off…