possible? force tunnel DirectAccess and VPN 2FA?

Hi,

We have a functional DirectAccess Server(2012R2) with force tunnel configuration.

The plan would be: all DA-Clients should use our "Updates-Services","Configurations","Surfing over our proxy" nothing more!

If the User needs more, he has to use a 2 factor authentication (VPNv2?,..)to get access to files and other services.

I Found this Scenario:
http://danstoncloud.com/simplebydesign/2016/06/01/breaking-the-myth-of-directaccess-end-to-end-scenario-part-1/
Until now I could not get it to run. :|

I also tested it, connect to DA. Then established a VPN connection but this ends shortly, after successfully connected to SRV2. Client Event: Error 829 (ERROR_LINK_FAILURE)

SRV1 = DA Server - Force Tunnel
SRV2 = VPN Server- SSTP

I think, with VPN Connection the systems checks, i am inside the corporation network -> disconnect DA (VPN lost) and reconnect DA...

would this possible?