Before installing upgrades to either the wiki or operating system software create a new snapshot of the server using the DigitalOcean console.
Follow the instructions as written on Updating Fedwiki
Pay attention to any errors generated by the npm install process. On April 14, 2019 I had a problem running wiki after upgrading and the root cause is that I was running an old version of nodejs.
I followed the instructions for installing Nodejs from a PPA provided by Digital Ocean. page 
If you need to re-build the server, create a new droplet from the snapshot you created prior to installing the upgrade.
After the droplet is built, shutdown the prior droplet then change the A record IP address for fedwiki.frankmcpherson.net. If you are not able to ping to server after the IP address is changed you need to reboot the PC you are using to clear the DNS cache so that the URL resolves to the new address.
After you log in to the server start Caddy. The current configuration requires that you access the site via URL rather than IP address, and you need to be running Caddy to access via HTTPS.
Finally, after you confirm the site is back up and running you need to enable backups of the droplet and you may want to destroy the prior droplet and remove any snapshots.