Reading again the whole documentation, experimenting almost everything, SOLVED by changing under
Phase1
General information
Interface
From WAN to 1.2.3.4 (Carp WAN IP)
Can't understand why, but I started to try everithing…
now it does not go online (internet) but it pings remote ips.. and I have to understand if it's possibile, and how, to resolve some address using the remote local dns... but it's another story.
F