Have you tried a different Ethernet cable, even though it works with the laptop? Or just turned it around, end-for-end, and reconnected it to PC and router? With everything connected, have you done a full power-off shutdown and reboot of PC and a full reboot of your router/modem after you reboot the PC? Now  look on back of PC at the link LEDs, next to the Ethernet jack: Off — A good connection exists between a 10-Mbps network and the computer, or the computer is not detecting a physical connection to the network.Solid green — A good connection exists between a 100-Mbps network and the computer.Solid orange — A good connection exists between a 1000-Mbps network and the computer. If LEDs are off (not detecting connection), open Device Manager and check if your network adapter is enabled and working properly. Then go to the Network Connection screen in Win 10, double-click the Ethernet listing and click Diagnose... Always possible the onboard NIC failed, meaning you'd have to replace the motherboard, or install a PCI-e x1 Ethernet card, or connect a USB2>Ethernet adapter which would be the easiest solution. 
My ethernet connection has stopped working. Error message says cable is unplugged or broken.  I connected the cable to my laptop (from router and got the internet wthout an error message, so liiks like cable is ok. No idea what to try next
ethernet connection