[problem] Traversing Routers using IPsec tunnel

Hello.

I have inherited a network configuration that has many elements that I am trying to wrap my head around. Networking isn’t my strongest suit but I can get by. However, I am having an issue and I was hoping someone could give me some next steps (or even better, a silver bullet).

The issue is that I have two sites. They are connected using IPSEC through two routers with access to the internet. The primary site, though, has a router to handle the LAN traffic that is connected to the WAN router. Traffic is showing up but I cannot figure out how to get traffic from the WAN router on the primary site to the LAN-RTR.

Here is a picture:
basicNetworkDiagram.PNG
Using the log and logging Filter rules, NAT, etc: If I ping from a device on the LAN-RTR I can see traffic in and out on the S2-RTR and the WAN-RTR. The return never reaches the LAN-RTR.

I know at this point there isn’t enough info to go on but ask and I shall provide.

Thanks.

Rob