Read the message first
Test connection shows a specific message. The next step depends on that text, not on repeating the same values.
| Message | What to check |
|---|---|
| Host unreachable or port blocked | Hostname or public IP, port 22, firewall. A LAN address is not enough: The NAS must be reachable from the PaperOffice datacenter |
| Timeout, or firewall blocking the connection | The same reachability. The test is waiting for a reply that never arrives |
| Connection refused, or port closed | The SSH/SFTP service on the NAS is not running, or the port in the dialog is wrong |
| Host not found | A typo in the name, or DNS |
| Authentication failed | User and password. PaperOffice AI authenticates SFTP with a password, not an SSH key |
| Connection OK, but the folder cannot be read | Base path and read permission for that user. An import source is tested read-only |
| SFTP subsystem could not be started | SSH answers, SFTP is not enabled on the NAS |
Next
Create or correct the mount: How do I connect a NAS as a storage mount?. Protocols: SFTP, WebDAV, S3 and IMAP.
Without inbound port forwarding for an import: Reverse-SSH, described in the reachability article above. BYOS stays SFTP.