OK, got it.
First of all, SSL has to be enabled in two places, which many of your documents do not mention, but it was mentioned here by rselbert. Thank you and please correct your documentation.
Secondly, the docu mentioned by vlkassingh shows RC4-MD5 as cipher option, which is no longer supported by at least IE and Firefox browsers. Selecting 3DES-SHA1 solves this issue and https works at last.
Should be so easy and becomes so complicated due to errors in documentation. Pity.
Thank you for the help!