I have finally figured out why Ubuntu likes to fail on Proxmox (and also Synology for that matter, which has a Virtualization hypervisor based on Qemu). Googling around got some solutions, but not this one,s o I decided to post it here.
During install, change the NIC settings from VirtIO to E1000. This will allow the install to complete and still have networking when install is done. You can also set this to NIC disabled, but I'm lazy and I just want to set it and forget it. E1000 is not optimized for speed nor reduced CPU, so don't leave it set like this unless you don't care.
