I'm trying to create an USB stick to install Lubuntu 18.04 completely unattended on machines without display. Most importantly, I want to install openssh-server during installation. I found the following documentation: Automating the installation using preseeding. But I think the description is somewhat incomplete. After following the tutorial at How do I create a completely unattended install of Ubuntu Desktop 16.04.1 LTS?, which is aimed at 16.04, I was able to automatically start the install process. However, during installation the account setup is incomplete and after the reboot I get stuck in a bootloop.
Could anybody provide me any resources or additional information on how to setup an unattended install on lubuntu 18.04?