We have recently rolled out Duo for windows login. The windows login function works great but we have notice a conflict with our Forticlient VPN client. We have forticlient connect before login enabled. Normally at the windows login screen below the username and password we had a button to connect to VPN before login. After installing the Duo client the button for VPN disappeared so we can no long connect to VPN before windows login. Uninstalling Duo brings the button back. Not even sure where to begin to troubleshoot this issue. It appears that the Duo client is changing something in windows to hide these options.
We are currently having this same issue and have been looking for a solution without any luck. Were you able to figure anything out about this issue?
Your VPN client likely supplies a credential provider to enable the connect before logon option.
Duo for Windows Logon doesn’t support being chained with other third-party credential providers, which is why those options get hidden when you install Duo.
You can configure Duo for Windows to allow use of other credential providers along with Duo, but note that Duo 2FA won’t get applied when you use one of these other credential providers.
Learn more about this configuration option here: Can I permit use of other credential providers after installing Duo?