Comprehension question with sftp connection in konqueror

[Volker Wysk]

Hi!

I've had ssh installed, and configured it to allow authentification with public keys only. Password authentification is turned off. I've set the SSH port to 3322.

It all worked fine (including sftp in konqueror). It still does, with the exception of sftp in konqueror. I can access my laptop from my desktop machine via ssh, scp and sftp, and vice versa. 

But when I open sftp://v@vaio:3322 in konqueror, I get this error:

   The requested operation could not be completed

   Details of the Request:

   URL: sftp://v@vaio:3322
   Protocol: sftp
   Date and Time: Friday 12 January 2018 20:24
   Additional Information: The host key for this server was not 
     found, but another type of key exists. An attacker might change 
     the default server key to confuse your client into thinking the 
     key does not exist. Please contact your system administrator.
   
"v" is the user, and "vaio" is the laptop.

In dolphin, I can open that sftp connection, it works.

I don't understand the error message. Is the "host key for this server" the public key of the server, which the clients have and use when establishing a connection? What does "another type of key" mean...?

Why don't the other programs complain?

Confused,
Volker