Password-type security really doesn’t have anything to do with this; it is about broadcasting your IPV6 address to the whole world which invites IP-based attacks of various kinds.
I turned off my firewall for a few minutes the other day when reconfiguring the LAN and there were tens of attempted attacks during that time and not even related to IPV6.
I am using IPv4.
As an aside, should I contact my ISP and upgrade?