slow wifi drivers wireless-ac 9560

Hi I've just got a NUC 8i7BEH kit) to replace my old windows 7 laptop, & I decided to try Linux instead of Windows. I have installed Mint 19 cinnamon, but the wifi connection is very slow (<2Mb/s vs 64Mb on the windows 7 machine, using the same router and speedchecker). Router is Virgin Media...