I have a Sonicwall with two WAN connections, a primary WAN (X1) and backup WAN (X2). I have defined a DMZ on X3 in transparent mode, to use some of the public IPs from the WAN. I can't use NAT since these are VOIP servers, which are allergic to NAT. I am noticing that I can only specify the IP range from the primary WAN. If the primary WAN is down, I can't use the backup WAN.
Despite having two WANs, I am not able to achieve network redundancy. How can I use public IPs from both WAN ranges in transparent mode? Is it possible at all?