AFAICT there was a single YouTube video that started this[0] and they mentioned explicitly several times that this mainly works because they put it in "the open internet" as a server. Disabling the firewall was the icing on the cake and yet that is all sites that reported this[1], no mention about how the computer was not behind, well, anything that a desktop in the last couple of decades would be (and most likely beyond that, i remember around 2002 when i had a modem, i had to visit a web page at my ISP to allow me open various ports as many things were disabled by default).
[0] https://www.youtube.com/watch?v=6uSVVCmOH5w
[1] https://www.xda-developers.com/connected-windows-xp-internet...