RV042 – how to broadcast UDP through VPN

Just like you have a route to the main gateway pointing all the traffic to the vpn subnet to the vpn gateway, you need a route in the vpn gateway pointing all traffic to the main subnet to the main gateway.

I did something similar recently, where I set up a VPN originating from a Linksys RV082 from behind a NAT router, so it's definitely possible.

Here are a few suggestions to consider:

• Ensure that NAT traversal (NAT-T) is enabled on the Peplink device
• If the Peplink devices supports IPsec, consider using that instead of the RV082
• Check that one VPN endpoint has keepalive enabled, or try sending traffic down the tunnel to bring up the security association
• You probably need to use the WAN port on VPN A to connect it to the LAN behind Router A. Normally, these devices will only listen establish VPN connections using their outside interface.
• If NAT-T is working properly, you don't need to do any port forwarding or NAT mapping on Router A. Try turning off your one-to-one mapping.
• You can get away with only one side of an IPsec security association being configured with a remote peer address. Try setting up VPN a with the remote address for Router B, then configure the security association on Router B to use 0.0.0.0 as the remote peer. It will just listen for a connection that way.

If it still doesn't work, check your logs on both sides, and verify that the Phase 1 and Phase 2 proposals are all using identical parameters.