Admin LAN via WAN

Hi,
Any idea about remotely discover & monitor all IPs, hosts & devices attached to all subnets that connected to Billion (BIPAC 5102) router which has single Static WAN IP & configuerd to DHCP & NAT on the LAN side, please? or I Should change the Billion with other router kind?!
Note: all Devices on the LAN side should not have static IPs.