ODK Central not loading on DigitalOcean while droplet is still running

1. What is the problem? Be very detailed.
I have been using odk central just fine for the past 3 months. But now it is not loading when I try to access with the same FreeDNS domain that has been working all this while.

2. What app or server are you using and on what device and operating system? Include version numbers.
ODK central on a Ubuntu droplet.

3. What you have you tried to fix the problem?

4. What steps can we take to reproduce the problem?

5. Anything else we should know or have? If you have a test form or screenshots or logs, attach below.

Hi @solomon

What error message are you getting (if any)? What your fully qualified domain name that you are using with ODK Central? Were there any DNS changes? Is your domain still active with the domain registrar?