Sending an ACME HTTP validation request to serial-club.ru results in an unacceptable redirect. This is most likely a misconfiguration of your web server or your web application.
Bad port number provided when fetching https://serial-club.ru:/.well-known/acme-challenge/letsdebug-test:
Trace:
@0ms: Making a request to http://serial-club.ru/.well-known/acme-challenge/letsdebug-test (using initial IP 212.8.246.33)
@0ms: Dialing 212.8.246.33
@160ms: Server response: HTTP 301 Moved Permanently
@160ms: Received redirect to https://serial-club.ru:/.well-known/acme-challenge/letsdebug-test