Calendar no longer syncing with CALDAV server after iOS update

zhamm66 wrote:

Trying to connect Apple Calendar on iPhone and iPad to existing Baikal CALDAV server that used to work (nothing changed on server side). After upgrade to iOS, calendar sync stopped working to Baikal CALDAV server, but google calendar sync still works. Tried improving SSL cert strength (TLS, encryption type, cert chains, etc), but nothing makes a difference. Installed Fantastical calendar on iPhone and used the SAME CALDAV settings to connect and it works fine. It's definitely a new bug in Apple Calendar.

Anybody seen this issue and have a fix (besides a hard refresh on iOS, that is not a solution)?

[Re-Titled by Moderator]

Here a good start for you https://sabre.io/support/ you can ask their support why it stop working and how to fix it, so you can use their calendar on a 3rd party app.