That makes me realise there is an incentive for ISPs to hold out on supporting IPv6. If IPv6 was widely supported then their IPv4 blocks would be worthless. I wonder how many will be holding out on deploying IPv6 until they can offload their still-valuable IPv4 addresses.
IPv6 adoption is just sad. Sharing an anectode: Back in 2002, I was using a 56k modem on a linux box 24/7 from home with a dialup flatrate. Being an avid IRCnet user, I setup an IPv6 tunnel with a tunnel broker (I think it was Hurricane Electric - it was before Aiccu was a thing) and connected to the IPv6 IRCnet servers. There was once a channel #uptime which was a contest: On start of contest, everybody in channel got voice - and the person to last hold voice would win (you lose voice when your TCP connection disconnects). Even so I had a forced disconnect every 24h, amongst over 100 users (mostly Servers, Bouncers, Universities etc.) I ranked 6th place in the end (after couple of weeks), because my ipv4 dialup was reconnecting fast enough to receive the buffered ipv6 tunnel pakets from the broker. Today I have no more IPv6 since SIXXS shut its doors a couple of years back, and my provider (o2/Telefonica) hasn't roled it out to me yet.
Looking back those 19 years, the availability and state of IPv6 has worsened for me - even though IPv4 shortage was known back then.
Same story here. I think I had IPv6 around 2000 with HE and then SIXXS, and my university back then already assigned IPv6 addresses. Now in 2021, I don't think I have had an IPv6 address assigned either at home or at work for quite some time.
It's hard to understand why they don't just push through since there clearly are no real technical problems as witness by those few countries with major providers that actually actively use IPv6 (only).