I have a need to route all network traffic destined from Site B (branch office) through our data center firewall at Site A. Both firewalls are SonicWalls. Site A is a NSA3600 and Site B is a TZ400. I've reviewed Sonicwall documentation on this using both site-to-site VPN and tunnel interfaces using route based options. It would seem that SonicWall is lacking (and the internet in general) on this subject with only a few things or old videos from 2014 (which seems like a 100 years ago).
I feel like this should be easier to do than I'm making it, but I've tried following the steps for the site-to-site VPN with NAT rule but it simply does not work.
I'm seeing documentation for unnumbered and numbered tunnel interfaces and I think I only need basic static routing - which they say to us unnumbered for - but don't see any documentation on how...