Slow Upload Speed

Hi, I recently just purchased the Gig speed deal. I also just bought a CODA56 modem with a NETGEAR Nighthawk Dual-Band WiFi 7 Router. I have my computer running through an ethernet cord and yet I've been capped at 40 mpbs upload speed. I just don't get it, but if I could get an answer as to how I can fix it, it would be greatly appreciated.