Could be a failing router (or modem if no router), failing cable or failing NIC.
Also, sometimes a NIC and whatever it is connected to have trouble negotiating a speed. In Device Manager right click the ethernet - Properties - Advanced tab - for the 'Speed & Duplex' property try different values beginning with '100 Mbps full duplex' and '10 Mbps full duplex.'
Also, sometimes a NIC and whatever it is connected to have trouble negotiating a speed. In Device Manager right click the ethernet - Properties - Advanced tab - for the 'Speed & Duplex' property try different values beginning with '100 Mbps full duplex' and '10 Mbps full duplex.'
