Fix device connected to lan port on ar300m?

Hello, i have a device that needs port fowarding.

Now I can plug in the device and select dest ip assigned to it and get it done…

But i have many of them and i cannot go.w/ the mac static ip route either…

Is there a way i can fix ip according to the connection? eth1(lan port cable) in this case

Go to LAN IP and set up Static IP Binding