If I create an FTP backend against a synology NAS, and issue:
rclone ls ftpnas:
I am presented with an error indicating the MCLD command is not supported.
The error is actually "MCLD " is not supported, as synology support explained to me after they examined a packet trace.
If I issue:
rclone ls ftpnas:/
it works as expected. There are some inconsistencies regarding the initial /.
Suggestion: if the pathname component is NULL, do no insert a SPACE between a command and the NULL. IE: avoid trailing SPACE on commands issued.