When deploying a vCenter Server Appliance (VCSA), you have two options for setting up a static network address: using either a hostname (Fully Qualified Domain Name) or just a static IP Address (e.g. no DNS). when a static IP Address is used, a DNS server is not required because we are NOT using an FQDN for the hostname but rather an IP Address. What option you selected?

Try like this: https://VCSA-FQDN/vsphere-client/?csp