• The FortiGate unit must be operating in NAT mode and have a static public IP address.

• The ISP must configure its network access server to forward L2TP traffic from remote clients to the FortiGate unit directly.

• The remote client must not generate non-IP traffic (Frame Relay or ATM frames).

• The remote client includes L2TP support with MPPE encryption. If the remote client includes Microsoft L2TP with IPSec, the IPSec and certificate components must be disabled.