Hi @zz386
Can you login via the Console on the control panel on DigitalOcean? Seems like something might have crashed your SSH daemon or maybe the firewall was enabled.

I resolved it. It turns out that when we create a droplet using the digital ocean UI, there is a section near the bottom which allows you to pick the SSH key that you have already added to your account. That step is not obvious when you haven’t set up SSH keys yet on digital ocean and start by creating your first droplets.
So I erased existing droplets, and created new ones again, this time with the SSH key that I had set up in advance. Now my SSH sessions start up fine on the droplets.

Probably there is a way to fix it without the above steps, but I couldn’t get that to work: ssh-copy-id username@remotehost fails because ssh username@remotehost already fails (in my case, connection timed out).