Why cannot Windows Defender not update it's definitions?

There are several reasons why Windows Defender might not be able to update its definitions, especially if you are encountering the error message about checking your internet or network connection. Here are some potential causes and solutions:

1. Internet Connectivity Issues: Ensure that your server is connected to the internet. You might want to check if you can browse other websites to confirm connectivity.
2. Firewall or Proxy Settings: Check if the URLs required for the Security intelligence updates are accessible through your firewall or proxy settings. You can refer to the Microsoft documentation for configuring your network environment to ensure connectivity with Defender for Endpoint service.
3. Primary Antivirus Conflicts: If you have a non-Microsoft antivirus solution installed, it might disable Microsoft Defender Antivirus, preventing updates. Ensure that Microsoft Defender Antivirus is set as your primary antivirus.
4. Manual Update Attempts: Try manually downloading the latest security intelligence updates from the Microsoft website. If this works, it may indicate an issue with the automatic update process.
5. Service Status: Make sure that the Microsoft Defender Antivirus services are running. If they are not, you may need to start them manually.
6. Windows Update Issues: There could be problems with the Windows Update service. Check if the service is running and troubleshoot any issues related to Windows Update.

If the problem persists after checking these areas, you may need to consult further troubleshooting resources or contact Microsoft support for assistance.