Check Cloud-Init override (VERY IMPORTANT on Ubuntu 20)

 Ubuntu 20 often overrides SSH settings here:

sudo nano /etc/ssh/sshd_config.d/50-cloud-init.conf

Change to:

PasswordAuthentication yes
PermitRootLogin yes

or 

sudo nano /etc/ssh/sshd_config

PermitRootLogin yes
PasswordAuthentication yes
PubkeyAuthentication yes
UsePAM yes

sudo passwd root

sudo systemctl restart ssh

sudo systemctl status ssh