NIST Control Covering SSTP VPN and using Windows passthrough authentication

VPN
1

We need to know what control addresses Windows SSTP VPN using the domain login passthrough credentials.
We have Duo MFA enabled on the VPN connection but need to know if we need to require entering the domain un/pw when connecting to the VPN or if we can enable credential passthrough.
Thanks.

2

You only need to force MFA once.