Hi @schweidj
if you install nethserver-nextcloud and create the virtualhost nextcloud.domain.xyz,
you can create a symlink to /var/lib/nethserver/vhost/nextcloud
ln -s /var/www/html/nextcloud/ /var/lib/nethserver/vhost/nextcloud/nextcloud
and add the new domain among those accepted by nextcloud
config setprop nextcloud TrustedDomains nextcloud.domain.xyz
signal-event nethserver-nextcloud-update
if you want the root of nextcloud in nextclound.domain.xyz it can create a file /var/lib/nethserver/vhost/nextcloud/index.php containing::
<?php
header ("location: http://nextcloud.domain.xyz/nextcloud/index.php");
?>