NE40 acts as NAT GW，the addresses of the address pool and Internet interface (Ethernet interface) belong to the same network segment. After configuring, some the users can connect Internet, other users cannot connect Internet. And then capture packets and detect the source address of the out packets is the interface address, these users can connect Internet, if the address of the out packets is that of the address pool, these users cannot connect Internet. Check the ARP on the uplink device of NE40, and detect there are no the corresponding entries in the address pool, only the entries of the interface address.
On NE40, the Ethernet interface configures "nat match-host" Command to make the Ethernet interface respond the ARP request of the address in the address pool.
The addresses of the address pool and Internet interface belong to the same network segment. The Ethernet interface connects with the exterior, at this time, the Ethernet interface should respond the ARP request in the address pool.