To always have access to the PC to which you want to connect, it must always remain on and never go into suspension.

It will therefore be necessary to modify the Windows Power options of the PCs that will receive the request for access to the remote desktop, for instance with the help of OpenVPN, or the PCs that will remain in the company. This guide explains how.

Windows 10: Windows Power Options

Open the Windows Settings

Windows Power Options

Select System

Windows Power Options

Select the Power and Suspension section in the menu on the left, and set the Suspension values to Never

Windows Power Options

Windows 7: Windows Power Options

Enter the control panel

Windows Power Options

If it is not set, set View by: Category as in the image.
Select System and Security to get to the following screen:

Windows Power Options

Select Energy saving options to get to the following screen:

Windows Power Options

Select Change combination settings for the active profile (the one in bold) to get to the following screen:

Windows Power Options

Check that Hibernate is set to never, otherwise set it and select save changes.