Cannot ssh with putty: hangs after entering password

Hello !
I am discovering HA through the HAOS flavour installed on a N40 minisforum box.
Installation went smoothly. I then installed Terminal & SSH plugin (9.4.0) and was able to ssh through the web user interface.
But I am stuck when I try to use putty: the terminal hangs after entering the password.
I have a very simple option file:

authorized_keys: []
password: mypassword
apks: []
server:
  tcp_forwarding: false

The log file show the following:

[21:27:30] INFO: Starting the SSH daemon...
Server listening on 0.0.0.0 port 22.
Server listening on :: port 22.
Accepted password for root from 192.168.1.96 port 53951 ssh2

So apparently no visible error here.
What am I missing ?