Thank you for posting your inquiry here in Microsoft Community, traininvain79.
I'm sorry to hear about the ethernet connection issue on the dock while connected to Surface Laptop 4. I appreciate the effort in performing the troubleshooting methods.
May I confirm if the Surface Ethernet driver is detected in device manager? Go to device manager > expand network adapters > look for Surface Ethernet driver.
Please perform the methods below:
- Run the Surface Diagnostic Toolkit while the Ethernet is connected to the dock.
- Run the System File Checker.
- Perform a network reset. Go to settings > Network & internet > Advanced network settings > Select Network Reset > Reset now.
- Try to disconnect everything (including the monitor cable) aside from the Ethernet Cable and see how it goes.
- Check Advanced settings for Ethernet. Go to settings > Network & internet > Change adapter options > Right-click the Ethernet adapter then choose properties > Click Advanced tab > Look for Energy Efficient Ethernet and Selective Suspend and make sure that they are both Disabled. > Hit "Ok"
- Install the drivers package manually.
- Check the specific OS build of your Windows Settings> System> About.
- Download the driver and firmware for Surface, choose Surface Laptop 4 and click download on the next page.
- Please choose the .msi file that matches your current OS Build and click Next.
- After the download, runand installthe .msi then Restart the Surface Device
Do you have a VPN used on your device?