russjudge.com has an AAAA (IPv6) record (2606:4700:3030::ac43:859a) but a test request to this address over port 80 did not succeed. Your web server must have at least one working IPv4 or IPv6 address. You should either ensure that validation requests to this domain succeed over IPv6, or remove its AAAA record.
A timeout was experienced while communicating with russjudge.com/2606:4700:3030::ac43:859a: Get "http://russjudge.com/.well-known/acme-challenge/letsdebug-test": context deadline exceeded
Trace:
@0ms: Making a request to http://russjudge.com/.well-known/acme-challenge/letsdebug-test (using initial IP 2606:4700:3030::ac43:859a)
@0ms: Dialing 2606:4700:3030::ac43:859a
@10001ms: Experienced error: context deadline exceeded
The domain russjudge.com is being served through Cloudflare CDN. Any Let's Encrypt certificate installed on the origin server will only encrypt traffic between the server and Cloudflare. It is strongly recommended that the SSL option 'Full SSL (strict)' be enabled.
https://support.cloudflare.com/hc/en-us/articles/200170416-What-do-the-SSL-options-mean-