After you upgrade vCenter Server and the vSphere Replication appliance, if the vCenter Server certificate or the IP address changed during the upgrade, you must perform additional steps.
To update the vCenter Server certificate, see vSphere Replication is Inaccessible After Changing vCenter Server Certificate.
If vCenter Server uses a static IP address, it preserves the IP address by default after upgrade. If the vCenter Server uses a DHCP address that changed during the upgrade, and the vSphere Replication Management Server is configured to use the vCenter Server IP address and not FQDN, update the IP address in the vSphere Replication Management Server.