Hi Adam, I think that by default Firefox will prompt you to provide your credentials for any site. There is a new feature for Windows 10 users to bypass this: [[Windows SSO]]. You could check whether that is enabled, either on the Settings page or in about:config (network.http.windows-sso.enabled). If the box cannot be checked/unchecked, or if a lock appears in about:config, there might be a company policy affecting the preference. You can check the '''about:policies''' page to see whether that is the case. Firefox also has a set of older preferences related to Windows Authentication to IIS servers. If your Firefox is configured to trust your internal servers, then you would be able to use them transparently in a regular window but if I recall correctly, you would be prompted to log in in a private window.