Show grafana visualisation in webview

Hello,
I want to display a grafana panel which is hosted on localhost:3000 in another webpage which is hosted on localhost:80. Website for localhost:80 is hosted on Microsoft IIS and i do not use any reverse proxy server. If i try to open the grafana site on localhost:3000 everything is running perfect, but if i try to open the “embedded” website in localhost:80 i get an error message. On the debugger of my internet brower i could see that obviously grafana can not reach a path to stylesheets because it wanted to connect somewhere on port 80 - not 3000… So maybe something in default.ini file is not correct. I assume either a reverse proxy server is necessary or some adjustments regarding the different port settings are necessary:

#The full public facing url
root_url = %(protocol)s://%(domain)s:%(http_port)s/

#Serve Grafana from subpath specified in root_url setting. By default it is set to false for compatibility reasons.
serve_from_sub_path = false

I also changed serve_from_sub_path to true, but no changes…

The WebView is created with a C# ASP.net code:

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
// Hier die URL der Webseite, die eingebettet werden soll
string url = “http://localhost:3000/d/fa6e3bd6-90fe-40b5-ad82-3fd843e22af2/evo-dashboard-test?orgId=1&from=1645956992944&to=1655786909276&viewPanel=46”;

    // Ein WebRequest erstellen, um den HTML-Inhalt der Webseite abzurufen
    WebClient client = new WebClient();
    string htmlContent = client.DownloadString(url);

    // Den HTML-Inhalt in das <div> Tag einfügen
    embeddedContent.InnerHtml = htmlContent;
}

}

Is it necessary to use a reverse proxy server in this case?