Hi everyone, I have a bit of an issue that I could use some help with. We currently have remote users that utilize an SSTP VPN connection to access our internal network. Once connected, those users are required to use an internal proxy server to connect to the Internet. The proxy server is Microsoft's TMG and utilized domain authentication. On our remote Windows clients we have their Internet Options configured to utilize a proxy as follows: Internet Options -> Connections -> LAN Settings -> No proxy configured at all Internet Options -> Connections -> Highlight SSTP Connection -> Settings Use a proxy server for this connection -> IP/Port of Proxy Server Firefox and Chrome are both configured to use system proxy settings. Here is my process to demonstrate the issues: Remote client workstation is rebooted. With the above configuration just after a reboot, a remote user that is not connected to the VPN can browse the Internet with Internet Explorer, Chrome, and Firefox. None of the browsers prompt for credentials. A remote VPN connection is then established. FF is opened and HTTP connections utilize the proxy server. However, HTTPS connections do not use the proxy server, but instead attempt to use the default gateway. FF does not prompt for credentials. FF is closed. Chrome is opened and can access both HTTP and HTTPS sites without issue. No credential prompt. Chrome is closed. IE is opened and can access both HTTP and HTTPS sites without issue. No credential prompt. IE is closed. Here's where it gets weirder... FF is then reopened. The VPN connection is still up. FF will prompt for credentials. Domain credentials are supplied and FF can now utilize the proxy for both HTTP and HTTPS connections. FF is closed. VPN is disconnected. FF is opened and cannot access the Internet as it is still trying to use the proxy server. FF is closed. IE is opened and can access the Internet. IE is closed. Chrome is opened and can access the Internet. Chrome is closed. FF is reopened and can now access the Internet. FF is closed. In summary, in the above scenario FF acts in an unexpected manner with regards to proxy usage when "use system proxy settings" is applied. However, Firefox begins acting as expected after IE is opened and closed. For example, connect to VPN, open IE, close IE, open FF, and everything works accordingly. Disconnect the VPN, open IE, close IE, open FF and everything works as expected. Any insight you can provide would be appreciated as it is affecting our FF users and the sooner we can achieve resolution the better. As a note, we've also worked through this issue with WPAD and proxy auto-detect. I've intentionally removed these from the equation to simplify troubleshooting. Thanks