Our current spacedesk Driver v0.9.61 for Windows 10 supports up to 16 client connection.
While spacedesk Driver v0.9.43 for Windows 8.1 only support up to 3 client connection.
If upon connection of your second viewer triggers a disconnection on previous viewer, then there might be a problem on the server/driver.
To further analyze this issue, please download the spacedesk diagnostic script here, then extract it.
Inside you will find spacedeskDiagnosticTool.cmd, just right-click it then run as administrator.
This script will start a debug view app to capture spacedesk debug traces.
On step 5 it will prompt you to reproduce the issue (by connecting the viewers until it disconnects), make sure to do this before pressing any key to continue.
After the script is done, a folder will be created on the same folder as the script file which contains various log files that we need for analysis.
Please right-click it -> Send to -> Compressed (zipped) folder, then attach the *.zip file on your next reply.
PS: "Attach option" should be visible below your text editor after your second post.