It would be helpful if you could provide more specific details about what you are trying to accomplish.
Also, it would be great if you could update the firmware to the latest version.
Typically, all LAN ports are part of a single LAN interface called "br-lan," which has a single IP address. If you want to assign a unique IP address to a single LAN port, you'll need to set up a port-based VLAN on that interface. This will allow you to set an IP address specifically for that port. You can set the IP address as static and configure the port to act as a DHCP server so that devices connecting to that port will be assigned an IP address from the VLAN subnet. Alternatively, the port can obtain an IP address from a DHCP server, assuming that the DHCP server is on the same network as the VLAN port and is reachable.
If you need more information on how to configure port-based VLANs, you can refer to the wiki page provided here.
To set up a static IP address and configure the port to act as a DHCP server on your RUT, select "static" from the "protocol" option and enable DHCP server at the bottom. If you want the RUT VLAN interface to obtain an IP address from a DHCP server, select "DHCP" as the protocol.