Hi Robert,
I'm Sumit, here to answer your query at the Microsoft Community.
It is pretty possible Smartscreen might be involved:
Windows Defender SmartScreen can block websites if it believes they're harmful. You can turn it off temporarily by following these steps:
Click on the Windows Security icon in the taskbar.
Select "Virus & threat protection settings."
Scroll down to "Control settings" and toggle off "Check apps and files."
Also toggle off "SmartScreen for Microsoft Edge."
Disclaimer: The steps mentioned above are intended to unblock a website that Windows Security blocks. However, it is important to understand that modifying security settings can expose your device and data to security risks. Proceed with caution and only unblock websites you trust and are sure are safe. Microsoft is not responsible for any harm or damage resulting from following these steps.