We have a 5510 configured with dual ISP's, one primary and one backup. We are using tracked routes for failover which is working fine. We also have a 5505 that we use for our public network access both public wireless and 802.1x on our wired switches. We are using our backup ISP to supply internet access to the 5505. We use one of our backup ISP's static IP's for our 5510 backup interface and one for the outside interface on the 5505. Both of these public IP's use the same default gateway. The problem is that when we try to establish a VPN connection to the 5510 from our public network (Backup ISP,) we are not successful. Its seems that the packets are reaching the 5510 but aren't being returned. When I disable the backup interface on the 5510, everything works fine. Any insight into this issue would be greatly appreciated.