When deploying a host with Ubuntu AutoInstall and deploying static dual stack (both IPv4 and IPv6) due to the current netplan generic template, the last addresses and nameservers blocks take precedence which means you lose IPv4 connectivity which means that if your foreman host is on V4 only the build will fail to complete during the late commands or possibly (unverified by me) your newly built system will only have working IPv4 after reboot

The NetPlan Generic template should be updated to change how the addresses and nameservers values are generated - i will submit a PR for this