Is it rusia2018.app or russia2018.app? Both are present in your post, and both point to your server …
None of the IPv6 variants of your domains allow access to the file.
~# curl -X GET -I -4 rusia2018.app/.well-known/acme-challenge/F-2TVGh_9TbmlACR31vZSIZiO--BHeQMGO_FYbHfUXs
HTTP/1.1 200 OK
Server: nginx/1.10.3 (Ubuntu)
Date: Fri, 25 May 2018 04:20:53 GMT
Content-Type: text/plain
Content-Length: 88
Last-Modified: Fri, 25 May 2018 03:04:13 GMT
Connection: keep-alive
ETag: "5b077d2d-58"
Accept-Ranges: bytes
~# curl -X GET -I -6 rusia2018.app/.well-known/acme-challenge/F-2TVGh_9TbmlACR31vZSIZiO--BHeQMGO_FYbHfUXs
HTTP/1.1 404 Not Found
Server: nginx/1.10.3 (Ubuntu)
Date: Fri, 25 May 2018 04:20:58 GMT
Content-Type: text/html
Content-Length: 178
Connection: keep-alive
~# curl -X GET -I -4 russia2018.app/.well-known/acme-challenge/F-2TVGh_9TbmlACR31vZSIZiO--BHeQMGO_FYbHfUXs
HTTP/1.1 200 OK
Server: nginx/1.10.3 (Ubuntu)
Date: Fri, 25 May 2018 04:21:05 GMT
Content-Type: text/plain
Content-Length: 88
Last-Modified: Fri, 25 May 2018 03:04:13 GMT
Connection: keep-alive
ETag: "5b077d2d-58"
Accept-Ranges: bytes
~# curl -X GET -I -6 russia2018.app/.well-known/acme-challenge/F-2TVGh_9TbmlACR31vZSIZiO--BHeQMGO_FYbHfUXs
HTTP/1.1 404 Not Found
Server: nginx/1.10.3 (Ubuntu)
Date: Fri, 25 May 2018 04:21:09 GMT
Content-Type: text/html
Content-Length: 178
Connection: keep-alive
This would indicate that your targeted nginx virtual hosts are not bound on IPv6 addresses (with listen
) and nginx is probably falling back to the default virtual host for IPv6 addresses.