it is really interesting. 

- What was the error message during the ping from Branch office?

- What is the result, when you start a ping from App server to Branch office?

- I think App server has static IP.. Is the gateway surely right in the App server NIC? 

-Did you add static route rule to windows route table before? (maybe server has wrong gateway to branch subnet)

- You mentioned already tried without firewall. Did you disabled all three firewall profile?