I am new to the forums and haven't done much posting in the past so any constructive criticism on etiquette would be appreciated! My end goal is to have a Cisco VPN Client connect through the Internet to a Cisco 2800 router that is sitting behind a SoHo router that is doing NAT (basically to my home through my ISP). I currently have a Cisco 2800 server that I am using to make a VPN connection to. This works fine from Cisco VPN client on a Windows PC when there is no Linksys router in between but fails when I place a Linksys BEFSR41 in between the Windows PC and the Cisco 2800. I have enabled VPN Passthrough on the Linksys BEFSR41, and enabled port forwarding on it for UDP 500 and TCP/UDP 4500. The Cisco 2800 is set to do nat keepalives and also to do udp encapsulation. The Cisco 2800 complains with ISAKMP errors which I believe are due to the Linksys BEFSR41 not correctly passing ESP (IP Protocol 50) and AH (IP Protocol 51) packets correctly. Since the Linksys BEFSR41 does not seem to be working with VPN Passthrough, I am looking for alternatives and thought about using DD-WRT. I cannot confirm with all my Googling whether DD-WRT on a Linksys WRT54G(S) will allow this setup to work or not and was hoping someone on these forums has some prior experience with this. Any help that anyone can give would be greatly appreciated! I hope I have given enough information, but if not, please let me know and I will try to provide anything else that is needed. Thanks everyone!