Does the Dangerous Site Ahead page match the description of what you see for phishing and malware sites? This article describes that page: [[How does built-in Phishing and Malware Protection work?]] Since that triggers based on host name, it's hard to understand why your local server would trigger it. Unless for some reason your local server's host name has a doppelganger on the outside and your DNS configuration isn't working as expected. Are you using DNS over HTTPS in both browsers?