I feel like I should be able to figure this out but...
I have two identical setups running HE tunnels. Both are running through DD-WRT routers. Before you panick, start laughing, start chiding, etc., know that I have had these working for years!
Indeed, one of the setups still works like a charm, with uninterrupted IPv6 access. However, recently, my other tunnel stopped working properly. Here are the specifics on the tunnel that is not working:
1. It is set up IDENTICAL to the tunnel that works.
2. From a computer behind the router, I can ping the IPv6 address of the router.
3. From a computer behind the router, I can ping both the Client IPv6 Address and the Server IPv6 Address of the tunnel.
4. I cannot ping any other IPv6 address. I get "Destination unreachable: No route".
With these being identical setups, routers, firmwares, and operating systems (CentOS Linux) on the computers doing the pinging, what are the possible causes for the failure of one to find a route? If you need/want any additional information, I will be happy to oblige. Thank you very much for helping!