I'm receiving a 503 service unavailable when my app connects to Appcelerator cloud services.
You can see this also if you go to:
Appcelerator Cloud Services, or ACS, have been down since October 1st. Emails have been sent out for a long time before that to warn you about it. You need to migrate your existing apps to Arrow.
Appcelerator Support can help you with that. Contact them via your direct channel (if you have a direct support channel) or use Intercom, it is the red bubble on the bottom right if you go to https://platform.appcelerator.com