[Daniel Filippelli]

Hello,

I suspect the issue is with the perimeter firewall (with the first NAT being performed) not having the proper route to the 2nd NAT’d network. I don’t usually work on Sonicwalls but a quick google search shows these 2 posts that you may want to take a look at:

https://community.spiceworks.com/topic/2306441-sonicwall-ipsec-behind-nat

https://www.sonicwall.com/support/knowledge-base/how-to-set-up-a-vpn-behind-an-existing-firewall/170505253857071/

Hope this helps.

Dan