Hello,
I'm not sure which certificate you're referring to.
If you want to replace the certificate used for HTTPS (port 443) access with a custom certificate issued by your internal PKI or signed by a public CA, you can follow this documentation:
https://docs.rcdevs.com/trusted-certificate-for-webadm-admin-portal-and-web-applications/
If you want to issue certificates using the WebADM CA, please refer to the following documentation:
https://docs.rcdevs.com/certificates/
If you need to generate a private key and a CSR, you can do so using OpenSSL.
If you also intend to replace the WebADM certificate used for port 8443 access, we discourage doing so, as it may have significant impacts on client integrations.
Regards,