I recently upgraded to Windows 10, and since then I've been having this weird issue where the internet just randomly disconnects,never had this issue before on windows 8.1 .
Motherboard msi z77a-g45
load the driver on a usb pen drive then uninstall the nic card do restart and see if windows will find a new device after if it ask for driver install the one you have .
if the connection still drops try reloading the intel chipset drivers and mei drivers and make sure windows is not turning off to save power the ethernet or pci lanes.