Well, what I do is disable ipv6. I don't want the possibility that this is misconfigured, especially if the defaults tend to be wrong. Maybe my router doesn't even respect my firewall settings, like this: https://community.verizon.com/t5/Fios-Internet-and-High-Spee... Maybe the customer is wrong, but this shouldn't even be a question.

The rare times I want something publicly accessible, I use DMZ or port forwarding.