Before installing a new spacedesk version, uninstall any previous version. 

This can be done on Windows Control Panel → Programs and Features or via spacedesk MSI installer → Remove .

For Windows 10/11:

spacedesk_driver_Win_10_32_v2116.msi for 32-bit platform

spacedesk_driver_Win_10_64_v2116.msi for 64-bit platform

For Windows 8.1:

spacedesk_driver_Win_8.1_32_v2111.msi for 32-bit platform

spacedesk_driver_Win_8.1_64_v2111.msi for 64-bit platform

Make sure to check the Firewall configuration before proceeding otherwise no client will be able to discover this Primary Machine nor connect to it.

Only on Windows 8.1 the dialog below will be shown and need to be confirmed.
These operating systems, also require a reboot after the setup has completed.