How to make fail2ban on OpenWRT?

Question

iptables

Hello.
Prompt (write) a simple rule for iptables to block the second and subsequent connections to a specific port. (for example 555).
//Try to break forwarded RDP. Ports are non-standard, but bots still find them.
because I always log in on the first attempt, I want to write a rule for iptables so that the second and all subsequent attempts to connect from the same IP are blocked for a day or two. (IP added to blacklist)