SSL сертификат, обновление Letsencrypt

Attempting to renew cert (forum.site.ru) from /etc/letsencrypt/renewal/forum.site.ru.conf produced an unexpected error: Failed authorization procedure. www.forum.site.ru (tls-sni-01): urn:acme:error:connection :: The server could not connect to the client to verify the domain :: DNS problem: NXDOMAIN looking up A for www.forum.site.ru. Skipping.
All renewal attempts failed. The following certs could not be renewed:
/etc/letsencrypt/live/forum.site.ru/fullchain.pem (failure)

All renewal attempts failed. The following certs could not be renewed:
/etc/letsencrypt/live/forum.site.ru/fullchain.pem (failure)
-------------------------------------------------------------------------------
1 renew failure(s), 0 parse failure(s)

IMPORTANT NOTES:
- The following errors were reported by the server:

Domain: www.forum.site.ru
Type: connection
Detail: DNS problem: NXDOMAIN looking up A for
www.forum.site.ru

To fix these errors, please make sure that your domain name was
entered correctly and the DNS A/AAAA record(s) for that domain
contain(s) the right IP address. Additionally, please check that
your computer has a publicly routable IP address and that no
firewalls are preventing the server from communicating with the
client. If you're using the webroot plugin, you should also verify
that you are serving files from the webroot path you provided.