Sets how often Webmin should request a replacement certificate from the ACME provider.

For hostname certificates, a renewal interval measured in months is usually appropriate. You can also choose days if you want Webmin to rotate the certificate more frequently.

IP address certificates are issued as short-lived certificates by CAs such as Let's Encrypt. Let's Encrypt currently makes these certificates valid for 160 hours, just over six days, and requires IP address certificates to use the short-lived profile because IP addresses can change ownership more often than domain names.

For IP address certificates, Webmin defaults to days and using 1 or 2 days is recommended so there is time to retry before the certificate expires. If Webmin is managing automatic renewal, the interval must be no more than 5 days. Manual renewal remains an administrator choice, especially if renewal is handled by separate automation or another operational policy.