I'm having the same issue on Focal Fossa using ubuntu-20.04-legacy-server-amd64.iso (md5sum 9d2b54506f8f9fdad6b72e45aff0f0de).
The only workaround which helps overcome the issue of not taking into account d-i netcfg/hostname string <desired host name> from preseed file is to specify hostname=<desired host name> on kernel boot command line.
Hi,
I'm having the same issue on Focal Fossa using ubuntu- 20.04-legacy- server- amd64.iso (md5sum 9d2b54506f8f9fd ad6b72e45aff0f0 de).
The only workaround which helps overcome the issue of not taking into account d-i netcfg/hostname string <desired host name> from preseed file is to specify hostname=<desired host name> on kernel boot command line.