The day before Thanksgiving, one of Amazon Web services server farms, the one in Virginia, started having problems and there were major outages over the next 36 hours.
This affected a wide range of IOT customers. Alexa routines, of course. Ring. But also a lot of third-party customers who used those servers for at least some of their users. That included:
Adobe
Amazon Photos
Amazon Alexa routines
Arlo
Hulu
iRobot
Lutron Login Services
Rakuten
Ring
SmartThings
Switchbot
Twilio
WeMo
and many more. 
But not all of the customers for any of those companies. Just the ones whose accounts were handled by those particular servers. And only for the cloud-based features hosted on those servers.
The thing is… That same region went down two years ago.
My rule as an engineer is glitches can happen. But when you have a major outage in the same place twice in two years, you’ve got a service defect. It might be hardware, it might be software, it might be training, it might be security… But something needs to be changed. 
BTW, if you lost one of your cloud service integrations with smartthings, you may need to go into the app and relink it. @jkp knows how to do that, I can’t use the app at this time.