Error "Could not connect to remote file system" while performing website backup.
The cause for the DisconnectError received from the host could be that the connection to cloud storage is slow, and because of this the host closes the ssh session as it is considered "idle". If this is the problem, a workaround is to add a ServerAliveInterval to the ssh config on the host. This will keep the sessions alive by sending fake traffic over the ssh connection at set intervals until they are closed by the SFTP client.
This setting would need to be added to the ssh config (/etc/ssh/ssh_config) under the Host section. For example (using an interval of 60s):
Host * ServerAliveInterval 60
The ssh daemon needs to be restarted for the change to take effect. For example on CentOS/RHEL/Fedora/Redhat the following command restarts SSH daemon:
# service sshd restart