With an old RVS4000 as an internet gateway and a second RVS4000 behind it, it was possible to establish an ipv4 VPN tunnel from each router to one at a similarly configured site, with the second VPN running through the first one. While this is not a recommended configuration, there were unusual requirements for doing it that way.
When I try this now, replacing only the gateway routers with RV340's, and RVS4000 routers behind them, both VPN tunnels do come up without error. The tunnel between the RV340 routers works as expected. But while the RVS4000 tunnel is up, it won't carry any packets, not even ping.
What difference(s) between the RVS4000 and the RV340 would cause this behavior? ACL rules for ESP, AH, IPSEC, ISAKMP? IGMP proxy? NAT-T? Note this happens even when the RV340 temporarily disables Application Control and other advanced security features.
