Not impossible depends on your provider and how they are interconnected with Nextcloud (they are I think at Hetzner). This peering stuff is a topic itself, what you can do, try hours where internet is less used (here you can test the speed: http://speed.hetzner.de/). Alternative is to use a proxy/vpn service (not sure if TOR is fast enought), increase timeouts, use manual updates, …
thanks. i downloaded apart the files and transfered it in download folder.
The zip folder is detected by update, so i was available to update my nc correctly