Migrate Nextcloud To Another Server

https://docs.nextcloud.com/server/stable/admin_manual/maintenance/migrating.html

Your Nextcould instance needs to be shut down completely. Including anything that runs along side it. 

Start by creating a new Nextcloud instance on your new machine. 

1)   On old machine, activate the maintenance mode. This should be done through the config.php file. /path/to/nextcloud/config

After waiting for 6-7 minutes for all sync clients to register the server is in maintenance mode stop the application and/or Web server that serves Nextcloud (if applicable). 

2)   Create a dump from the database and copy it to the new machine

https://docs.nextcloud.com/server/latest/admin_manual/maintenance/backup.html

3)   Copy all files from your Nextcloud instance, the Nextcloud program files, the data files, the log files and the configuration files, to the new machine