Windows 10 includes Windows Security, which provides the latest Microsoft Defender Antivirus protection. Your device will be actively protected from the moment you start Windows 10. Windows Security continually scans for malware (malicious software), viruses, and security threats. In addition to this real-time protection, definition updates are downloaded automatically to help keep your device safe and protect it from threats.
If you disabled automatic Windows Updates over metered connections, it will also prevent Microsoft Defender Antivirus definition updates from being automatically installed via Windows Update over a metered connection.
Starting with Windows 10 build 20175, a new group policy was added that allows Microsoft Defender to update and communicate over a metered connection even if you disabled automatic Windows Updates over metered connections.
This tutorial will show you how to enable or disable allowing Microsoft Defender Antivirus to update and communicate over a metered connection in Windows 10.