I work for an ISP one of Fortigate Biggest customers in EU.
One of my customers had previously configured a /30 public IP .1 for ISP router interface and .2 for Fotigate and all worked fine.
The customer needed a backup router and we provided him one.
Now I had to configure both routers for VRRP with private range +NAT connecting via dialer with one single IP because /30 is not enough ( 3 IPs minimum for vrrp).
How can I go about this without affecting his network?