Hi @zhiweny1122,

I’ll assume you’ve actually installed certbot already so we can just continue with the actual configuration for installing a wildcard certificate.

Let’s say we have a test domain example.com. To actually install a wildcard for it, we’ll need to run the following command from the droplet

sudo certbot certonly --manual -d *.example.com -d example.com --agree-tos --no-bootstrap --manual-public-ip-logging-ok --preferred-challenges dns-01 --server https://acme-v02.api.letsencrypt.org/directory

This should be enough for the wildcard to be installed.

Regards,
KDSys