If you get failed to attach disks while attempting a HyperV Instant Recovery
reg add HKLM\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters /v AllowInsecureGuestAuth /t reg_dword /d 00000001 /f
This will allow the system to bypass the GPO preventing us from connecting to the share.
This is usually seen as error 0x80004005 when attempting to browse to the appliance.
Adding "samba" as the username and password for the Unitrends IP under Windows Credentials can sometimes help with this as well.