How to set up VPN on Demand on IOS 7 plus Synology VPN server?

Question

iOS

Hello. There is a Synology NAS. It has a VPN Server L2TP/IPSec. I want to connect from my ios device to my vpn server on demand, i.e. automatically. Tried to figure this out, but not much success. As far as I understand, the VPN server must be IPSec with certificate authorization, right? For ios, a profile is created, in which the on demand checkbox is checked and the appropriate profile is selected. In theory, everything seems to be clear, but in practice I can’t implement it, because. my Synology VPN server does not support certificates. Tell me, is it possible to somehow organize an automatic connection to VPN without a certificate? Or maybe there are some other ways or crutches?