[aborsy]

NAT busting is a minus. If apps can create holes in your network and “bust your NAT,” your network is not well secured; you should disable UPnP and filter egress.

Also, you gain simplicity but give up to coordination servers, that can be a privacy and security problem.

[rwbhn]

Tailscale isn't using UPnP. See https://tailscale.com/blog/how-nat-traversal-works/

[istjohn]

That was an interesting read. Turns out they do use UPnP, but it's just one of many tools they turn to when other techniques fail.

[trulyme]

Sidenote: this is a fantastic writeup.