I call it: "Dead Tunnel Syndrome", where tunnels appear to negotiate successfully but the tunnel itself is corrupt blocking traffic, either all traffic or just certain ports or host IP's. When this happens, the only solution is to reboot the RV34x. The only way to tell a tunnel is "healthy" is to constantly ping IP hosts on the other network, though I've seen cases where an echo is returned but actual traffic is blocked. The "Dead Tunnel Syndrome" usually surfaces after repeated disconnects when the RV34x becomes so scrambled that it is no longer able to create a healthy tunnel.
I have three RV340 sites exhibiting the same symptoms. The RV042's these RV340's replaced NEVER did this; as their tunnels, the ones they 'initiate' that is, were always rock solid. The RV042/82 firmware is obviously "mature" in the sense that these types of instability bugs were long since cured. As for the RV340 series, site-to-site and client-to-site VPN was completely rewritten, fertile ground for 'memory leaks' or instability to creep in.
I've also noticed, on occasion, one RV340 site even corrupts its PPPoE WAN connection, again requiring a manual reboot of the router. It all points to buggy firmware. In which case, all we can do is wait and hope that Cisco addresses these issues in an upcoming firmware release, hopefully soon!
