I’ve run a small public web server for well over a decade and never had any issues with hackers.
It’s never late to get hacked or an attack or a problem with your ISP router firmware. I don’t think that’s an excuse.
receive backups from my other servers
You can simply do cronjob and scp user@server:/path/to/backup . to get things from server to your local network, I don’t see the need to expose your router to the public. For a web server, there are cheap VPS providers for less than 5 dollars a month, and you save up energy, hardware, and improve safety at home.