I had the same problem with an old computer I wanted to install Astaro on. But instead of making the bootdisk, I moved the harddisk and the networkcards from the "firewall-gonnabe" to a more modern computer. Then I did the first part of the installation, moved the harddisk and networkcards back and continued the web-based setup.
I had the same problem with an old computer I wanted to install Astaro on. But instead of making the bootdisk, I moved the harddisk and the networkcards from the "firewall-gonnabe" to a more modern computer. Then I did the first part of the installation, moved the harddisk and networkcards back and continued the web-based setup.