According to the error message, the server offers only unsupported SSL/TLS protocols. DAVdroid doesn’t allow SSLv3 anymore (as it’s now unsecure, see NIST recommendations). Is it possible that the server doesn’t offer TLSv1+ but only SSLv3 or below?
I can connect to this server using Evolution, so I know it is working.
Evolution used SSLv3 only (yes, no TLS!) even at the time when POODLE was discovered. However, this was soon patched.
By the way, I think the path should be
/principals instead of