Hi asdfghjxcvbn,
As the Ethernet Controller is not listed in Network Adapters, please check under Other Devices. If it is present under Other devices, please try installing the driver. If it fails to install the driver, please share the Hardware Id of the device listed under Other devices. You may right click the device and click on Properties -> Open Details tab -> Click on Property and select HardwareId and share the information here.
If the Ethernet Controller is not listed under Other devices as well, you may consider replacing the LAN daughter board. I hope your computer is under warranty.
Hope this helps. Please reply with the findings.