So we have one post office on 2018 and others on 2014 across various sites and a couple of countries.
Since we upgraded our biggest site to 2018 our caldav server will not allow us to connect to it and add users at the 2018 site.
Should 2014/2018 be able to talk to the same calendar server? I assumed they could.
If not and we are not going to upgrade some of the other sites to 2018 in the near future do we need to look at a 2nd caldav server? I didn't think there was a separate caldav server and that one should happily work with both.