Hello @phil, @StevenHendrickx
to login to the MervisOS command line via SSH, you need to enable the SSH first. This behaviour changed in the image 1.7, where the SSH is disabled by default as a security measure. In older images, the SSH was enabled.

To enable the SSH, you need to create file named "ssh.txt" in the partition called "boot" on your SD card. This is the same process as with Raspbian. You cannot enable the SSH once the UniPi is running. You need to take out the SD card, put it in your PC a create the file there.

The default username is "unipi" and password is "unipi.technology". To switch to the "root" user, run sudo bash.

Is this description sufficient or do you need to clarify it a bit more?

Best regards,