Add-WindowsCapability failed

Add-WindowsCapability might fail in some scenarios in SCCM environments. Try the following to workaround the issue

Set-ItemProperty HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU -Name UseWuServer -Value 0 -Force
Get-Service wuauserv | Restart-Service -Force
#Try Add-WindowsCapability with the feature you would like to install, CertificateServices is listed as example 
Add-WindowsCapability -Online -Name Rsat.CertificateServices.Tools~~~~0.0.1.0

RSAT feature list

• Rsat.ActiveDirectory.DS-LDS.Tools~~~~0.0.1.0
• Rsat.BitLocker.Recovery.Tools~~~~0.0.1.0
• Rsat.CertificateServices.Tools~~~~0.0.1.0
• Rsat.DHCP.Tools~~~~0.0.1.0
• Rsat.Dns.Tools~~~~0.0.1.0
• Rsat.FailoverCluster.Management.Tools~~~~0.0.1.0
• Rsat.FileServices.Tools~~~~0.0.1.0
• Rsat.GroupPolicy.Management.Tools~~~~0.0.1.0
• Rsat.IPAM.Client.Tools~~~~0.0.1.0
• Rsat.LLDP.Tools~~~~0.0.1.0
• Rsat.NetworkController.Tools~~~~0.0.1.0
• Rsat.NetworkLoadBalancing.Tools~~~~0.0.1.0
• Rsat.RemoteAccess.Management.Tools~~~~0.0.1.0
• Rsat.RemoteDesktop.Services.Tools~~~~0.0.1.0
• Rsat.ServerManager.Tools~~~~0.0.1.0
• Rsat.Shielded.VM.Tools~~~~0.0.1.0
• Rsat.StorageMigrationService.Management.Tools~~~~0.0.1.0
• Rsat.StorageReplica.Tools~~~~0.0.1.0
• Rsat.SystemInsights.Management.Tools~~~~0.0.1.0
• Rsat.VolumeActivation.Tools~~~~0.0.1.0
• Rsat.WSUS.Tools~~~~0.0.1.0