When I try to make an L2TP Road Warrior connection from a laptop connected to the Internet via a Vodafone 3G connection the Smoothwall server gets as far as saying “ISAKMP SA established” but then fails with “Cannot respond to IPSEC SA request because no connection is known from [Smoothwall RED IP address]”.
The 3G connection is a NAT’ed connection and I wonder if this is a problem. Though NAT traversal should prevent any problems.
I tried connecting through a PC connected directly to the internet through the same ADSL modem that the Smoothwall box is connected to and it works, giving the message “IPsec SA established”. But I don’t know if this proves that it is a Vodafone issue, or a NAT issue or what.