Update your Drivers
Specifically, your motherboard and ethernet drivers. Head over to the manufacturer's website for your brand of motherboard and search for your specific model, download and install the drivers. Making sure to have the ethernet drivers correct for your motherboard installed is incredibly important. You'll usually find them under Support or Drivers on the manufacturer's website.
Uninstall your Network Adapter
Go to Device Manager by right-clicking on the Windows icon and selecting it. Right-click and uninstall the network adapter for your ethernet found under "Network Adapters". Now, select Action>Scan for hardware changes, and let Windows find your updated ethernet driver and install it.
Check Adapter Settings
Right-click the Windows icon, select Network Connections. It will display a list of your adapters. Right-click the one you've been having issues with. Select "Properties". Make sure that Internet Protocol Version 6 and Internet Protocol Version 4 are checked. If they aren't, do so.
Update/Reinstall VPN and/or Antivirus/Firewall
If you use a VPN, uninstall the adapter and software and reinstall it. Part of upgrading to a new OS is making sure you've got the latest versions of a great number of integral applications, and VPNs can be rather particular about how virtual adapters are set up.
If you have antivirus software, or have third-party firewall software, do the same. An uninstall and clean-install of AV/firewall software can address some of the issues with restoring internet connectivity after an OS upgrade.
Renew your IP
You could accomplish roughly the same effect by running the network troubleshooter, but let's walk through the more in-depth for releasing and renewing your IP address, as this may also help as a quick fix.
1. Press Windows Key + X and select “Command Prompt (admin)”.
2. Type ipconfig /release and hit Enter.
3. Then type ipconfig /renew and hit Enter.
4. Type Exit and hit Enter.
