Can you explain what the problem is? I see many HTTP 200 OK responses in your log for both domain names. I also successfully connect to both of your domain names.
It is not. But, in the log they used test domain with http and robert domain (*) for https. They both work like that but I agree the test domain is not in the cert so would show errors if tried with https.
(*) The first post shows VirtualHost for oc domain but the log is robert for https. I see both oc and robert working fine and both those names are in the cert.
Yes, the log is different. Sorry for the confusion. I first tested the configuration with robert.koller.ch and extracted the log. But to continue using robert.koller.ch, I set up oc.koller.ch as domain name for https. It behaves exactly the same.
As osiris pointed out you have mixed content. Your website can be connected with HTTPS just fine. That means your certificates are fine. But take a look at this site
Please check your log yourself: in one of the two parts there are requests for .css files visible while in the other part there are none. They are blocked by the client, so no, the logs wouldn't be identical.
Change http:// in your code to https://. Note that HTML/server side scripting is not the expertise of this Community
Because without HTTPS there is no mixed content possible? Please search the meaning of "mixed content" if you don't know what it is and educate yourself