Switch from Dropbear to OpenSSH on DietPi.
Dropbear SSH is a great solution for embedded devices, but sometimes I want to use a plain old OpenSSH server.
To use the full-blown OpenSSH server you need to install it using the software center.
Execute dietpi-software
utility.

Open SSH server menu.

Select desired SSH server.

Accept changes.

Execute install step.

Remember to update service settings after the installation process is complete.
Additional notes
scp
scp
needs some attention from your side, but does not require full-blown OpenSSH server.
$ scp data.tar.gz milosz@10.0.0.8:~/backup
bash: scp: command not found lost connection
To use OpenSSH secure file copy install openssh-client
on server.
server$ sudo apt install openssh-client
sftp
sftp
needs some attention from your side, but does not require full-blown OpenSSH server.
$ sftp milosz@10.0.0.8
bash: /usr/lib/sftp-server: No such file or directory Connection closed. Connection closed
To add OpenSSH secure file transfer program install openssh-sftp-server
on server.
server$ sudo apt install openssh-sftp-server