We have a spark 15xx series. Where we live the ISP gives us a dynamic ip address and we have bought a static one for our site to site vpn. its not on the same subnet. normally with other devices, like juniper and fortigate, we just enable unnumbered ip and it picks up the fix ip, or we can create a loopback interface and configure the ip on it. and the site to site vpn comes up. In checkpoint we saw a config where we could use another ip for site to site, but when we use it it doesnt initialise the vpn. Any help will be great.