Can't access files, webdav not working

Hi, I’m trying to use Nextcloud on an o2switch server which doesn’t use WebDav. So naturally, I’m getting a

Your web server is not yet properly set up to allow file synchronization, because the WebDAV interface seems to be broken.

Is there any way to bypass this? I read about Sabre/Dav but I don’t know how to activate it.

Nextcloud version : 13.0.5
PHP version : 7.1

Is this the first time you’ve seen this error? : Yes

Thanks for your help,

I’ve got the same probleme with o2switch and nextcloud 14. I cant acces too “all files”, no think show in the rigth place (juste the circle turning) and i can’t add file.
Is the nextcloud web interface use webdav too show file?

Nextcloud have is own webdav/caldav server.

I think that o2switch have a webdav activated and conflict with nextcloud.
I know there is a caldav server for agenda with the mail server.

Is yours nextcloud work?