I'm not sure why you quoted your words as mine, but OK...
Please clearly explain what port you wish to open on this device (I'm guessing RDP 3398/udp).
Please explain this - how port 80 on a public IP to a bank gets involved, if your devices are all on LAN.
Yes, and you were told:
So please explain why you want to place rules in the OpenWrt - as if it will control any firewall between the 2 devices on the same broadcast domain?
Also, the 2 IPs you show are not in the same subnet, so it brings more confusion regarding your "devices are on LAN side" description. Lastly, you still haven't explained why you're trying to backdoor the IP of a bank to get to a desktop.