Make sure that your key algorithm of choice is supported. On Ubuntu 20.04 or later you must explicitly allow the use of the ssh-rsa algorithm. Add the following line to your OpenSSH daemon file (which is either `/etc/ssh/sshd_config` or a drop-in file under
`/etc/ssh/sshd_config.d/`):
Make sure that your key algorithm of choice is supported. On Ubuntu 20.04 or later you must explicitly allow the use of the ssh-rsa algorithm. Add the following line to your OpenSSH daemon file (which is either `/etc/ssh/sshd_config` or a drop-in file under `/etc/ssh/sshd_config.d/`):