You used to be able to telnet into the Tritton/Argosy NAS.
With recent firmware you can no longer do that.

The firmware that came in my box was accessible via telnet, but 6-1013
and later are not. I ran a port scanner on it, and the only ports that
are open now are the FTP and HTTP ports. I think maybe they don't want
people poking around in their system.

Perhaps your Landisk is the same, and simply does not allow telnet
access.