This policy setting allows you to specify if the AES cipher can be used to encrypt data sent over the Mobile VPN. If you ...

"This policy setting allows you to specify if the AES cipher can be used to encrypt data sent over the Mobile VPN.  If you enable this setting, the Mobile VPN  can use AES data encryption.  If you disable this setting, the Mobile VPN  cannot use AES data encryption.  If you do not define this policy setting, the default behavior is to allow both AES and Triple DES (3DES) encryption.  Note:  If both AES and 3DES encryption algorithms are explicitly not allowed, the Mobile VPN fails."