The only setup difference between Iphone and Android is the L2TP preshared key.This is empty at Android side.
*Go to Settings -> Wireless & Networks -> VPN Settings
-vpn name: “set a vpn name”
-vpn server : “set firewall ip”
-ipsec preshared key:” set l2tp key ”
-l2tp preshared key : “disable”
You will be able to connect from Android.