Aircard 810S as simple router?

In normal operation, the Aircard provides IP addressing to clients on its LAN and hides their addresses behind its own WAN side IP. This is problematic if you want to initiate connection from Internet to a LAN side device. Is there any way of turning the Aircard's natting off such that it simply routes?  This would be of little use for an internet-connected Aircard but would be useful for a private WAN.