I've got a Cisco 870 (non-wireless) setup with a typical home config, broadband cable (dhcp client), DHCP server, NAT, FW, etc... I also currently have a site-to-site tunnel setup.
I use the Cisco VPN client 4.6.03.0021 on some computers on my internal network to VPN into my work. The VPN client is setup to use IPSec over UDP. I can hit our VPN end point at work and authenticate, but IKE SA negotiation fails (phase 1). This used to work before configuring the tunnel. Additionally, if I swap out the 870 for my old linksys WRT54G, VPN client works just fine.
I also removed all ACLs from the WAN int, as well as turned off the FW, but still have the problem. Everything else I use through the 870 works fine, i.e. games, IM, inet, p2p, etc... another VPN client I have that uses VPN over SSL even works fine.
What needs to be configured on the 870 to allow IKE SA to complete?
Thanks a ton to whoever can help!