I will never, ever understand this "single-packet authentication" "port knocking" fetish. It has never made sense. Bin it, along with fail2ban, and just set up WireGuard. Your network authentication should not be a fun game or series of Rube Goldberg contraptions.
Every complex services running, is a door someone can potentially break. Even with the most secure and battle tested service, you never know where someone fucked up and introduced an exploit or backdoor. Happened too often to be not a concern. XZ Utils backdoor for example was just last year.
> Your network authentication should not be a fun game or series of Rube Goldberg contraptions.
If there is no harm, who cares...