The first thing to try would be to restart your modem and router that connects to your internet service provider. This can be accomplished either with a built-in power or reset button on the device(s) or simply by power-cycling the device(s) for about (15) seconds. If that does not resolve the problem, you can try to uninstall and reinstall your computer's network adapter. To perform this action:

1. Type device manager in the Cortana search box and then open the device manager control panel app
2. Open the network adapters category and locate the device you want to uninstall and reinstall - you may be looking for terms such as ethernet controller or 802.11 in the name
3. Uninstall the network adapter to be reinstalled. If it asks you whether to delete the driver software, leave the check box unchecked so as to NOT delete the actual driver files from your computer. Confirm to proceed with the uninstall
4. Restart the computer. The network adapter will be redetected on startup and reinstall the necessary drivers from the system

If the above steps are unsuccessful in resolving the problem you may want to contact your internet service provider for further assistance