How to forward port 22 through a router under OpenWRT?

Question

firewall

Everyone, good day!
There is a TP-Link router stitched under OpenWRT. External IP is white, I set up access to the router via SSH from the Internet with grief in half. Now you need to configure SSH access to servers located on the local network of this router.
If I understood everything correctly, then I need to make some kind of conditional SSH port (for example, 23454) and direct it to port 22 of a specific server with a fixed IP (for example, 192.168.1.100). After, from the outside, connecting via SSH to the "WAN-IP of the router: 23454" I will go directly to a specific server.
Question: what do I need to add to the /etc/config/firewall file of the router in order for this scheme to work?
Thank you!