I managed to get kubernetes up and running.
Well hidden in a github issue (which I can’t find now) I found that I have to delete some files and that I have to set masterAdress to the hostname, as the cert-deamon seems to not be able to generate a cert for an IP.
Also I learnt that apiserver.advertiseAddress has to be the IP (as I changed it to the hostname as well in first try).
So now the kubernetes is up and running.
Thanks for pointing me to k3s anyway, I might give it a shot.