External URL in Dashboard
Set up your dashlet
If you enter an external URL in the custom URL dashlet and embed it as an iFrame, you’re guaranteed to get a content-blocked error message. But if you enter the address of the checkmk server itself, e.g. https://yourCMKserverIP, you will see the Apache-Server default site.
The workaround: Just create a HTML file in the document root of the Apache server with the following content, for example:
<iframe src="https://www.checkmk.de" width="800" height="600">
for the moment it works just with fixed width&height perhaps anybody has more knowledge to make it responsive.
And in the Custom-URL-Dashlet you enter https://yourCMKserverIP/mycustomframe.html as URL and activate the iFrame option
That was it