Extern access issue, webdav or nextcloud desktop/android client can't connect

I have an Nextcloud instalation in a web space from my ISP (ovh.com). I’ve installed Nextcloud 13 and at web access, it works (some warnings here).

But I can’t access throught clients (nextcloud desktop client, nextcloud android client, dolphin client, webdav access). Maybe I need setting any config file to garant external access?

I have no console access to the site.

ty for your attention,