relay: no support for wildcard certs
The current implementation of derper does not support wildcard certs.
This describes the possible challenge methods and which are compatible with *.domain.tld certificates.
Manual certificate mode is available as workaround for now.
This is still active, we only do the TLS-ALPN-01 challenge
Making sure the issue is up to date: This basically boils down to it not being worth supporting the DNS challenge directly and writing whatever number of integrations with DNS providers. The solution is to write a custom cert resolver that just hot-reloads the cert every day and putting certbot in front with the right DNS config to handle the renewals.