My Windows 10 laptop worked fine to get internet network through an Intel(R) Ethernet(2) I219-LM cable until applied the updates. Now when I put the system into sleep mode and then wake it up, the wired network ends up at 10Mbps and is not reconnecting at all. To get rid of that temporarily, I have to make a rebooting but the same problem appears minutes later. The Network Adapter troubleshooter reports “Ethernet doesn’t have a valid IP configuration” message.
How to fix Ethernet loses internet connectivity after sleep mode in Windows 10
* First make sure your Ethernet driver is up to data. You could download the latest version of the driver from your manufacture site and install it. My friend reloaded the related driver on Lenovo ThinkPad and it works.
* First unplug your ethernet cable, connect Windows 10 to any WiFi network and keep the wireless adapter active, then plug in the cable again. Now the LAN connection works smoothly and actually take the priority.
You can also re-configure the power setting
* From your desktop, type sleep into cortana search box or Start menu.
* Select the Power and Sleep settings from result.
* Click on Additional power settings, and then click “Change plan settings” with your current profile.
* Click on “Change advanced power settings”, expand Wireless Adapter Settings > Power Saving Mode, and change that.