I have hit another bigger problem:
to get my certificate from startssl.com I need to verify ownership of the domains I want to get a certificate for but unfortunately most root server providers assign you a default name within their domain, mine is i.e. hxxxxxxx.stratoserver.net and startssl.com only offers validation for domains, not sub domains.
They say you could get a certain paper signed by the domain owner and then come back but that would be quite a difficult process and I am not sure if Strato will comply.
What other slutions are there? i.e. getting a spare domain just for "naming" my server? woudl that do? But I guess then I need to change not only the hostname but a lot of other services's configuration, right?