Comment by alias_neo

> Unfortunately, disabling uPnP these days is too much of a hit to convenience, so I looked for other solutions.

Don't do this, there is no good reason to run UPNP if you care about security, turn it off and learn to manage a firewall.

If the author really cares, go one step further and replace the ISP owned router with something with more control.

Finally, if one cares about the software one's NAS runs, build or buy from someone like TrueNAS.