I’ve tried using latest CalDav app with Nextcloud 12.0.4 and Apache. App-Password was set before because my nextcloud is using 2factor auth.
CalDav throws me an error log (URLs sanitized): Link
Works well here with our clients (Android -> Davdroid, Thunderbird -> Lightning, iOS etc).
2017-12-15 09:06:57 20483 [HttpClient] <-- 404 Not Found https://myurl.host/remote.php (244ms)So, where is remote.php located?
Which Android Client are you using and what did you set with it to access CalDAV on your server?
Well after retrying again some days later it worked out of the box. Seems like the DDoS protection sometimes kicks in out of nowhere.