IP address shows as unknown in Tools>Options>Virtual Appliance>Configuration
Make sure the DNS records for the Virtual Appliances (VAs) are correct.
Make sure the VMware Tools are up to date on the Virtual Appliance.
Make sure the IP address of the Virtual Appliance is reported in the vSphere client on the Summary tab of the VM.
Remove the unknown VAs from vRanger (Tools > Options > Configuration (Virtual Appliance)) and add them back in.