How to get internet speed in C#?

You could do it like this.

This example downloads a web page, measures the time needed
and then calculates the speed in bytes per seconds.

Stopwatch stopwatch = new Stopwatch();
            
stopwatch.Reset();
stopwatch.Start();

WebClient webClient = new WebClient();
byte[] bytes = webClient.DownloadData("http://www.codeproject.com");

stopwatch.Stop();

double seconds = stopwatch.Elapsed.TotalSeconds;

double speed = bytes.Count() / seconds;

MessageBox.Show(string.Format("Your speed: {0} bytes per second.", speed));

Refer: Detecting network connection speed and bandwidth usage in C#[^]