When I disabled IPv4 a few weeks ago, I couldn't use: HN, GitHub, Reddit, Discord, Duckduckgo.
Update - 23 Aug 2023 — Today, we are pleased to announce the general availability of IPv6 support for the Docker Hub Registry
Apparently it can be done now, I wont be finding out in a hurry.
In corporate-y environments it allows for easier tracking of user-MAC-IP mappings for auditing purposes. If you use SLAAC there is no auto-logging as the client simply picks an address itself.
One way to do tracking with SLAAC could be to SNMP scrape/trap ipNetToPhysicalTable of RFC 4293. Another would be 802.1X or MAC authentication (interim) accounting via RADIUS (RFC 2866).
There are other advantages too, like if you want to assign specific addresses to specific devices without having to configure each device separately.
SLAAC just tells the endpoint device to self-assign an address and to roll with it. For example, there’s no way to pass in DNS servers with SLAAC.
None of those sites have v6 though, so you'll need some form of backwards compatibility running to reach them. Presumably you were missing that.
I recently had to setup a non-encrypted website because I have a few old devices that can no longer do HTTPS.
IPv4 on local networks will probably exist for a very long time.
That sounds like they haven't been updated for TLS>1.1 – if that is the case then rather than going all the way down the HTTP you could enable TLS1.1 (and maybe 1.0). It is open to POODLE/BEAST/others that way, but still have some protection and the site's configuration differs less from the rest of your infrastructure.
Unless the site is completely internal only of course, in which case just sticking with HTTP may be less faf.
And I have an old Blackberry Bold that now show current electricity prices, so I know when to starte my washing machine. That can also run on own webserver.
As a side note, barely anything supports TLS 1.1 but not TLS 1.2