Wikipedia, the free encyclopedia anyone* can edit, blocks T-Mobile's entire IPv6 address space of 2607:fb90/32 from anonymous editing and account creation and has for years.[1] For reference, that is 79,228,162,514,264,337,593,543,950,336 or 2^96 IPv6 addresses. Most T-Mobile customers use native IPv6 without knowing it, so they have de facto blocked an entire nationwide ISP. Since they now sell home internet, this is not just limited to mobiles anymore. Wikipedia has published a sob story[2] where they justify these actions, claiming it's so difficult to ban IPv6 users because the addresses dynamically change when the device is restarted and the address space is so large, and T-Mobile's use of proxy acceleration, they are left with no choice but to ban the entire ISP's customer base, all 110 million of them. Their "advice" is to have a friend on another ISP create an account for you on a desktop computer. Why even allow access over IPv6 at all at that point, if they can't deal with the management of it? This is all especially hilarious and hypocritical given this quote:"The Wikimedia Foundation believes that the principle of net neutrality is critical to the future of the open Internet."
[1] https://en.wikipedia.org/w/index.php?title=Special:Log&page=...
[2] https://en.wikipedia.org/wiki/Wikipedia:Advice_to_T-Mobile_I...