Prerequisites for ACME Certificate Issuance

Before you configure ACME, make sure the following requirements are met.

Network connectivity: The device must be able to resolve and reach the ACME server URL through the selected IP network interface. Make sure DNS servers are configured on that interface.
HTTP-01 challenge: The certificate's domain name must resolve publicly to the device, and the CA must be able to reach the device on port 80.
If a web server is already listening on port 80 on the IP interface, the device uses webroot mode.
Otherwise, the device starts a standalone listener on the IP interface.
DNS-01 challenge: Upload credentials for a supported DNS provider to the ACME Profile (see Uploading DNS-01 Credentials to an ACME Profile). DNS-01 is required for wildcard certificates.