We have a LAN-LAN VPN working fine between two sites (A and B), both with a Draytek 2850n. At site A there is a static route in the 2850n which routes two subnets (10.3.0.0/24 and 172.16.0.0/24) to a third party Cisco 877 (and works properly). At site B we want to be able to route across the VPN and to the Cisco for the relevant subnets. I have set up the subnets in the "More" section of the VPN profile at site B, and a TRACERT confirms the traffic is reaching the 2850n at site A, but goes no further.
There are no load balance / route policies in place on either 2850n.
How can we configure the 2850n routers so that the traffic will pass from site B to site A's Cisco?
Here are the relevant parts of the routing tables (WAN routes removed and WAN IPs redacted) from site A:
Key: C - connected, S - static, R - RIP, * - default, ~ - private
* 0.0.0.0/ 0.0.0.0 via [Site A WAN IP] WAN1
S~ 10.3.0.0/ 255.255.255.0 via 10.152.112.2 LAN1
C~ 10.152.112.0/ 255.255.255.0 directly connected LAN1
S~ 10.152.115.0/ 255.255.255.0 via [Site B WAN IP] VPN-3
S~ 172.16.0.0/ 255.255.255.0 via 10.152.112.2 LAN1
Here's site B:
* 0.0.0.0/ 0.0.0.0 via [Site B WAN IP] WAN2
S~ 10.3.0.0/ 255.255.255.0 via [Site A WAN IP] VPN-1
S~ 10.152.112.0/ 255.255.255.0 via [Site A WAN IP] VPN-1
C~ 10.152.115.0/ 255.255.255.0 directly connected LAN1
S~ 172.16.0.0/ 255.255.255.0 via [Site A WAN IP] VPN-1
Thanks in advance for any advice.