RemoteAugmentation.cs

IWebDriver driver = new RemoteWebDriver(new Uri("http://localhost:4444"), new ChromeOptions());
ICustomDriverCommandExecutor customCommandDriver = driver as ICustomDriverCommandExecutor;
customCommandDriver.RegisterCustomDriverCommands(ChromeDriver.CustomCommandDefinitions);

ChromiumNetworkConditions networkConditions = new ChromiumNetworkConditions();
networkConditions.IsOffline = true;

Dictionary<string, Object> parameters = new Dictionary<string, object>();
parameters.Add("network_conditions", networkConditions);
customCommandDriver.ExecuteCustomDriverCommand(ChromeDriver.SetNetworkConditionsCommand, parameters);

try
{
    driver.Url = "https://www.saucedemo.com";
    Console.WriteLine("The navigation should have thrown an exception");
}
catch (WebDriverException)
{
    customCommandDriver.ExecuteCustomDriverCommand(ChromeDriver.DeleteNetworkConditionsCommand, null);
}

driver.Url = "https://www.saucedemo.com";