Our internet/network setup uses a Speedstream 4200 adsl2 modem running in bridged mode, with a netscreen 5GT firewall handling the pppoe authentication and all other routing/firewall policies etc.. Some client pc's inside the LAN use Cisco VPN client with transparent tunneling and IPSEC over UDP to connect to some remote sites. Recently I had to replace the speedstream and I purchased a Netcomm NB6plus4. To my disappointment the cisco VPN connections no longer work. The client authenticates but no network resources are available. I assume the problem is the fact that the netcomm does not support IPSEC tunneling.
What I would like to know is what to look for in a modem which will have the required functionality. I see some refer to "IPSEC passthrough", is that sufficient for my purposes?