Hi! There could be several reasons that would cause your site to be “unreachable.”
Often times, when you make changes to DNS, it can take several hours for the changes to fully propagate. DNS servers also cache information, so if you were accessing your site before the change, your DNS servers might have stale info.
You can test your domain name DNS here:
Those should return with the IP address you configured in DigitalOcean Domains. If not, you may need to double-check your changes and make sure the record for domain.com has a record (an “A record” or a “CNAME”, perhaps) that resolves to the correct place.
If those tests are successful, then you may need to wait until your DNS servers refresh. If possible, try to confirm that it works with a colleague or friend on a different internet connection.
Hope this helps, let us know if you have further questions or issues.