VPN IPsec from a dynamic IP with UMTS router

[sandman42]

Hi,

I'm experiencing with 60E, and specifically with IPSec VPNs. While I did a site-to-site VPN to a cisco ASA with no problems, I'm having problems with a UMTS router who is also VPN terminator.

Speciifically, since IP is dynamic, this VPN on cisco fws lands on the DefaultL2L and so on.

How can I configure the VPN on FortiOS, i.e. make the routers connect to central site which has a fortinet fw?

As an example, I have 192.168.10.0/24 on the central site and 192.168.11.0/24 on remote site.

Can you give me a hint?

Thanks

Franceso