vpn ipsec

Using Marshmallow and MIUI 8 how can we use a VPN connection permanently? In Lollipop we add an to put an IP address on the host and another IP on the DNS server's. After select always on VPN. In Marshmallow I can't make the same type of connection. What am I missing? Thank's.

Hello, i am unable to establish a vpn connection to a cisco asa fw via ipsec. Vpn stettings on the asa should be correct as an ipad is able to connect. Are there any known issues regarding the builtin vpn client? I'm using this ROM: xiaomi.eu_multi_MI5_6.10.27_v8-6.0.zip