Phone a friend! Go to a friend's house and run nmap (zenmap for a GUI if you like, https://nmap.org/download.html most common OSs supported). Do the same for them in return.

You might also like to explore this: https://www.shodan.io/ and if you have some time on your hands this: https://www.kali.org/

Most consumer routers will by default block a connection _from_ the Internet. They use a private address range and apply NAT to outgoing connections, so explicit configuration is needed to do something with an incoming connection.

Well. UPnP does end up being supported on many consumer routers.

The big issue for consumer routers is, admittedly, the shoddy quality of the firmware and the fact that even on the occasion where vulnerabilities are fixed, those releases often do not get installed.

And that is why they implement UPnP to punch holes through it to avoid users having to manually configure routers.

Say it with me

NAT Is Not A Firewall

I believe you, but I have little expertise. Could you explain or give examples why?

Some people would state "this box is not on the internet" while it actually is only behind nat. As soon as you have two such boxes being able to communicate, for instance "two laptops playing online together" you realize they ARE on the internet. With home-routers allowing UPNP and such things, its even more open than that.

So the general idea that things will be safe from being behind nat is more or less wrong, unless you have 100% control over all possible traffic generated from the inner host(s), at which point you could have had it without firewall more or less. Will your robo-hover never phone home, never look for tuesday patches, java updates, OTA firmwares or talk to some license server or whatever? Then nat is ok, but if any of this can happen in some situation, then it is "on the internet" even if it started out behind nat.

It moves a machine along the scale from unreachable closer to unprotected-and-exposed-to-everything even if it's not all the way there.

Unfortunately thats the opposite of my experience with the camera