(Plesk for Windows) Limiting Bandwidth and The Number of Connections to a Website
To avoid excessive usage of bandwidth and protect your website from denial-of-service attacks, you can limit the bandwidth usage of a website and the number of simultaneous connections to it.
To limit bandwidth usage and the number of connections to a website:
Go to Websites & Domains > the website whose bandwidth and connections you want to limit > the "Hosting & DNS" tab > Bandwidth Limiting.
Next to "Maximum bandwidth usage", clear the "Unlimited" checkbox, and then specify the maximum speed a website can share among all its connections. The speed is measured in kilobytes per second.
Next to "Connections limited to", clear the "Unlimited" checkbox, and then specify the maximum number of simultaneous connections to the website.