In some cases, some web site administrators will want to limit the number of concurrent connections available for a certain website to prevent the site from becoming overloaded and suffering from decreased performance, or for development purposes. This can be easily accomplished through Internet Information Services.
Navigate to Start -> Administrative Tools -> Internet Information Services (IIS) Manager.
Once open, expand the Server Name by clicking the plus-sign next to it, then expand Web Sites, select the site you wish to change this setting for, and click Properties.
Once the Properties dialogue box is open, click the Performance tab.
By Default, the amount of current connections will be set to Unlimited. Click the radio button next to Connections limited to: and set the your preference for the number of connections. For now, let’s set it to 500. Once entered, click OK.
You have now limited the number of available concurrent connections to your website.