As per the title, if the Windows Retpoline method of mitigating Spectre is enabled, DT cannot mount SCSI or IDE drives. It gives the "insufficient resources to create target connection" error. The Retpoline mitigation is described here: https://techcommunity.microsoft.com/...ws/ba-p/295618

The mitigation is purely optional at present, but it does sound as if Microsoft are planning to enable it automatically at some point.