Well, 4U1UN has quite a history. Although I really don't understand why this station counts for a DXCC. It's no separate country or island it's just an organisation. I guess it's the same reason as the sovereign Military Order of Malta that counts for a DXCC as well. I think it's just a "collectors" item to be honest. Read more about the station here:
http://www.4u1un.net/
Although the site is not updated after 2015 it contains a lot of info about the station before 2020. I believe at the moment the station is operated remote via the internet.
The proof:
