I just got a new IP address from our ISP to assign to the WAN side of our Sonicwall NSA 2400 (SonicOS Enhanced 188.8.131.52-17o). I wanted to just assign it to the same X1 WAN interface as the existing IP, but couldn't figure out how to do that (multihome?). I then tried to add it to the X2 interface as a secondary WAN interface, but am getting an 'Invalid IP' error when I try to save the interface record. What's strange is that if I change the subnet mask from a /30 (255.255.255.252) to something at or below 255.255.255.250 I no longer get the error. Of course if I do that I can't communicate with the default gateway.
My existing IP is 64.x..x.x/255.255.255.252. My new IP is 174.x.x.x/255.255.255.252. All I really want to do is allow inbound HTTP/HTTPS to a new server that is in addition to the one we already have receiving that type of traffic on the existing IP. In the past I've done this on Sonicwalls using the 1-to-1 NAT configuration, but a.) that screen doesn't show up on the Sonicwall NSA 2400, and (more importantly) b.) when I've done this in the past it was with WAN IPs that were all in the same block, so there were no additional default gateways, etc.
Hope that makes sense to someone.