Upload speed terrible since OS upgrade

Hi, I’ve upgraded the OS in my Mac Pro early 2009 to El Capitan from Mavericks and have found my upload speed has taken a big hit, dropping from 160 Mbps to around 4. It’s an ethernet connection to the router which I’ve reset without any improvement and it’s a fibre connection. I also run Windows 7 via VM Fusion and I’m still getting full speed upload there. I’m stumped as to why my VM has full upload performance while the host OS does not. Can anyone offer advice?

Many thanks,

Dave