At Settings > Client Portal > Domain URL there is an option to optionally configure a separate client portal domain. But unfortunately there is nothing in the documentation about this option.
How do I need to enter the domain? billing.domain.com or http://billing.domain.com or https://billing.domain.com or
What DNS settings are needed? I guess an A-Record to the IP address of the INv5 server. Or is a CNAME record needed?
Does this require settings to the NGINX configuration?