I have multiple clients (using Windows XP PPTP config) trying to access the same VPN concentrator. All of the clients are behind a firewall that is NAT'ing the outbound Internet connection. Is this possible?


It is not possible if all the PPTP clients are on the same LAN and behind a single NAT firewall public IP. The RF660 can not accept multiple PPTP clients that are coming from the same IP address.


Is this an RF660 limitation or just PPTP? Is there another alternative on the RF660? IPSec LAN->LAN will not work because we are running into address conflicts.


This is a limitation of the RF660.

If you have a windows server on the LAN, you can enable PPTP server on it which can support multiple PPTP clients coming from the same IP address. You will need to disable the PPTP function on the RF660 and let windows server handle all the PPTP connections.