But for me, I think most of the people who are facing Error 503 are just service unavailable Error 503.
Refreshing or reloading the page might help if it's a temporary error.
Try restarting your Wifi modem.
Contact the admin(startor) of the website.
If that's because of popularity then site admin might be searching some fix for that error, so come back later.
If you want a clear insight of troubleshooting the error then please try to check the following blog post of mine. Hope this works. Link to post: Error 503
If link does not work then try copying and pasting in the browser Link: http://anglitch.com/error-503-service-unavailable/