In my latest move a few months ago, I had to transition to a new ISP, and with that transition came the dreaded carrier grade NAT jail cell. My IPv4 was essentially blocked from self-hosting anything I expected to be accessible from outside my home network, but the good news is: my ISP does supply a dedicated IPv6 for me. I turned it on and started binding some services to it, and while those mostly worked without a hitch, I began seeing unusual behavior from my non-IPv6 applications.