Using AES on VPN connection

Robbo777

Hi, i'm wondering where is the option to use AES encryption for a VPN tunnel using SSTP when connecting to my DC on server 2012. I've created a NPS and NAP etc... everything is setup and works, a client is using my certificate for public/private key exchange for the encrypting of a symmetrical encryption key but it says in the options on the Network Polices section on the NPS that it uses MPPE and there doesn't seem to be any other choice? AES is the best out there and i'm wondering what i have to do to change it to that?

Thanks