I see you are having problems streaming using the Slingplayer for Desktop on one of your four computers running on Windows 10 OS. The Slingplayer for Desktop application is now only for re-configuring you Slingbox. To stream any Slingbox you can go to our website Slingbox.com
Its as simple as downloading the Slingplayer for web plug-in and start enjoying your programs. Windows OS did issue out two updates, this will cause an issue when trying to connect to your Slingbox if not updated properly. In some cases the updates will go through without the request or approval of the owner. Although this last Windows update, some customers needed to manually update their PC. I advise to check your Window updates by clicking on Cortana >entering "Window updates">then click on "check for updates" to make sure you do have the latest version available. I will be posting a link to further guide you in downloading the Slingplayer for Web Plug-in.
Sling Media Support