Having the same issue here. SSH won't start on a brand new Ubuntu 20.04 LXC container. I also tried a Ubuntu 18.04 container, as well as a 20.04 privileged container, all having the same issue.
Host info:
Code:pve-manager/7.0-10/d2f465d3 (running kernel: 5.11.22-3-pve)
I can attach to the LXC container from the host and start SSH manually. If I enable the service (systemctl enable ssh) it appears to work, but after a reboot of the LXC, SSH is dead.
Code:● ssh.service - OpenBSD Secure Shell server Loaded: loaded (/lib/systemd/system/ssh.service; enabled; vendor preset: enabled) Active: inactive (dead) Docs: man:sshd(8) man:sshd_config(5)
Exactly mate
But if you install for example one lxc from this link, it will work. Test it, just so i can have your opinion:
https://uk.images.linuxcontainers.org/images/
(at least i tested with the last Debian 10 version from that link and it worked with no problems!)