Slow speed through ethernet on RaspberryPi 4

I've recently upgraded my internet to fiber to get 1G.

I've moved some of my machines to ethernet connections, to gain
more speed. On my windows 11 machine I can get 800/900 Mbps. But on my Pi I'm
 getting much slower speed.

Any ideas why, and if I could improve the throughput to the ethernet to take
 advantage of the higher speed internet ?

Getting 203 down / 273 up this morning :-(

Better than what I got with my previous provider; but I should be able to do
 even better.