I have a cisco 1721 connected to a cable modem, and forming a site to site VPN tunnel with an aSA 5505. I was using EZVPN. A couple days ago, traffic stopped passing through the tunnel, although the tunnel was up. I tried setting it up as a sraight lan to lan, and still the same problem. I even changed where it terminated, from an ASA to a concentrator on a different ISP, and the exact same result: tunnel shows up up, the concentrator shows bytes in both directions, no errors, but just no traffic. I have tried several different encr/hashing methods and no change. The ASA and 3k concentrator are working, as I can connect using the client w/o an issue. Ther wierd thing is the 1721 is not using a hardware crypto card, so its ALL in software, and other than the VPN problem it is passing traffic normally. I also doubt the ISP just randomly started blocking VPN traffic, espeically since the tunnel comes up. Anyone seen this before or have an idea as to what the problem could be, or is it just likely the 1721's crypto engine is bad/corrupt? It is running 12.4 advanced security.