I went back and forth with the people at Owncube doing troubleshooting, for the Caldav calendar they provide using Owncloud's software. Apparently, I've got the URL and the settings and password and everything right, but every time I try to connect I get "7- Server returned unexpected response."
They say they've gotten it to work with Evolution in Ubuntu. Is this a regression or incompatibility of some kind? What should I do?