My nextcloud server (back then it was still running ownCloud) stopped syncing calendars with Thunderbird/Lightning a few weeks ago. Now I just learned, that my hosting provider (Hostpoint) upgraded from Apache 2.2 to Apache 2.4 which now supports http2. This upgrade seems to be what broke the sync.
Is there something I can do on the nextcloud server side to get the sync working again?
I have also added a comment to an existing bugreport for thunderbird (https://bugzilla.mozilla.org/show_bug.cgi?id=1106727). As the sync works with Android and iOS devices still works, TB certainly is also involved in this issue.
The nextcloud server is the latest version. TB/Lightning as well. Tested with Windows and Linux (Kubuntu 16.04LTS)