Hello,
Thank you for reaching out, I’m sorry to hear about the issues that you’re experiencing with your site!
A 503 status code, or “Service Unavailable” error, means that the server is overloaded or under maintenance. If the server is not under maintenance, this can indicate that the server does not have enough CPU or memory resources to handle all of the incoming requests, or that the web server needs to be configured to allow more users, threads, or processes.
These types of issues can be troublesome to pinpoint, however we have some guides that will assist you with reviewing your Droplet’s resource usage and logs to find out what the likely causes could be:
How To Monitor CPU Use on DigitalOcean Droplets
https://www.digitalocean.com/community/tutorials/how-to-monitor-cpu-use-on-digitalocean-droplets
How To Use Top, Netstat, Du, & Other Tools to Monitor Server Resources
https://www.digitalocean.com/community/tutorials/how-to-use-top-netstat-du-other-tools-to-monitor-server-resources
How To View and Configure Linux Logs on Ubuntu and Centos
https://www.digitalocean.com/community/tutorials/how-to-view-and-configure-linux-logs-on-ubuntu-and-centos
Feel free to open the Support ticket for us to see on your Droplet. We will not be able to access it from community.
Hope this helps!
Cheers,
Lalitha

by Justin Ellingwood
Monitoring a server's resources is an important task for every administrator. There are many command line tools made for this purpose. This guide will cover some of the more popular utilities for monitoring your VPS.