Now, I can also login with key and without password.

My problem is solved, I can login with ssh and password.
The directory /etc/ssh/sshd_config.d contains a file
with the name 50-lxc-android-config.conf
This file contains the line "PasswordAuthentication=no"
I changed the "no" to "yes" and restarted the sshd with
"systemctl restart ssh".

Strange that the account "phablet" can be used but doesn't exist in
/etc/passwd.

"Password Authentication yes" with a space between Password en Authentication cause that the sshd doesn't start.
With "PasswordAuthentication yes" without the space the sshd runs.

But in Putty I still get "Disconnected: No supported authentication methods
available (server sent )

I will try to place a public key on my Ubuntu touch device.

@kristatos
With "systemctl start ssh" the ssh.service is running.
"netstat -atn | grep LISTEN" give
tcp 0 0 0.0.0.0:22 0.0.0.0:*

"ifconfig wlan0" give
wlan0: flags=4163<UP, BROADCAST,RUNNING,MULTICAST> MTU 1500
inet 192.168.50.92 netmask 255.255.255.0 broadcast 192.168.50.225

On an other system in the same network, the command
"ssh sysadmin@192.168.50.92" give
sysadmin@192.168.50.92: Permission denied (publickey).

So I have contact with the sshd on my Ubuntu touch mobile.

Now I had to solve the publickey problem.

My Google Pixel 3a is installed with Ubuntu touch and works OK.
It is possible to connect with SSH from an Ubuntu Linux system to the Ubuntu touch mobile?

Yes, please reset my password en send me a temporary password by E-mail.
Many thanks.

I got an E-mail from info@ubports.com with the subject "Welcome to Ubports".
In the E-mail was a link,
I followed that link and I was in the forum.

https://forums.ubports.com/user/linuxlion/edit/password

Now I have an account, but I never saw a field to set a password.
But to set a password I had to fill my current password.
How can I set a password when I have no current password?