Error 404: Not Found - Parallel Execution

I'm trying to run tests in parallel by using Nunit3.

    public void test()

    public void Initialization()

        InternetExplorerOptions caps = new InternetExplorerOptions();
        caps.IgnoreZoomLevel = true;
        caps.EnableNativeEvents = false;
        caps.EnablePersistentHover = true;
        caps.AddAdditionalCapability("‌​", false);
        _webdriver = new RemoteWebDriver(new Uri(""), caps.ToCapabilities());

I'm running my tests on IE11 browser and I'm getting the following error only when using the Parallelizable parameter.

OpenQA.Selenium.WebDriverException : Unexpected error. Error 404: Not Found

The browsers are being opened on both Nodes(selenium grid) and even navigating to the URL, but then it fails. What am I missing?