Only expose HTTP/HTTPS, homu hooks, and SSH to the outside world.

# ufw allow ssh
# ufw allow "Nginx Full"
# ufw allow 54856/tcp
# ufw enable

To disable the firewall rules, run ufw disable. Use https://linuxize.com/post/how-to-setup-a-firewall-with-ufw-on-ubuntu-18-04/ to aid in setting up new rules as necessary.