I found this article recently whilst discussing a question about socket reuse using
DisconnectEx() over on StackOverflow. It’s a useful collection of the various configuration settings that can affect the number of concurrent TCP connections that a server can support, complete with links to the KB articles that discuss the settings in more detail. It’s a bit out of date, but it’s probably a good starting point if you want to understand the limits involved.
Note that I’ve never had to tune or tweak the default settings (apart from setting
MaxUserPort to allow more outbound connections).