Oh , that's of course a strange problem I so do not know applications from other web on my server . Since I have just discovered that the SSL encryption for Baikal Server also does not work , even though the browser has taught my self-created certificate CALDAVZAP is in this constellation probably rather than what the local and private network . Tom Von: Ján Máté [mailto:jan.mate@inf-it.com] Gesendet: Dienstag, 21. Juni 2016 15:29 An: davclients@inf-it.com Betreff: Re: [Inf-IT DAVcl] External vs. Internal Internal/external IP is NOT related to cross-domain setup. JM On 21 Jun 2016, at 14:08, zyrixx <zyrixx@gmx.net> wrote: Hello, so far I can use with my CALDAVZAP either internal or external with my URL. If it is to function internally, must in the href my internal URL stand for external use that is only possible in the href with the external URL. Does this have to do with the topic Cross Domain and then the Apache configuration has to be changed? Best wishes Tom