I can create working days, but not "not working" days?

You are talking about vacation days, public holidays etc?

Yes, holidays for example, or one day a reservation is not possible.

Thanks for the quick reply.

Yes, you're right, this is not possible right now. It should be part of the base Reservations plugin. I've just added this new feature to the Issues: https://github.com/vojtasvoboda/oc-reservations-plugin/issues/47

Ok, thanks!

That would make it usable for me, because without blocking certain days / periods I can't use it. If you have an estimate I would like to hear.