Typically all computers connected to a router are protected by the router’s firewall. To allow a computer on the Internet to connect through the router to a specific computer it is necessary to either manually forward the required ports (link below), or to place the device/computer into the Cradlepoint’s Demilitarized Zone (DMZ). For more information about adding a device to the DMZ, refer to this post.
Configure Port Forwarding on a Cradlepoint router
Links of Interest