Windows 10 users from around the world have been reporting that they are unable to connect to Windows Update. When they attempt to update, Windows would report that it could not connect to the update service. Windows blogger G..nter Born feels that this issue could be related to Windows Defender as numerous people have reported having issues installing a Windows Defender update before receiving this error in Windows 10. Switching to Google’s public 8.8.8 DNS service as described below can solve the problem. Users in Japan and the U.K. are reporting the same problem.
Source: https://www.bleepingcomputer.com/news/microsoft/many-windows-10-users-unable-to-connect-to-windows-update-service/