When trying to add a Windows Server optional component it fails. Checking the DISM log shows the error message “DISM Package Manager processed the command line but failed. HRESULT=800F0954”

This can be resolved by enabling the policy “Specify settings for optional component installation and component repair” and ticking the option “Download repair content and optional features directly from Windows Update instead of Windows Server Update Services (WSUS)”.

This can be done locally on the server (using gpedit.msc) or by a centralised group policy. The policy is under “Computer Configuration\Policies\Administrative Templates\System”.

After amending then gpupdate the server and try installing the component again.