If it is back up at Amazon maybe a local reset?

Power down all Sonos, reboot router and controller then power up your Sonos. 

Thanks Stanley. I’ve done that and no joy. I’ve also now disconnected the skill and re enabled and now Alexa can’t even see my Era 100.  🤷‍♂️

Let's all talk in that thread.

same problem here. All Alexa integration on sonos speakers stopped. I have deleted the skill and now it will not reload. I am sure this is the tip of the iceberg! I hope sonos are working on it

Best to wait I suggest. 

good news, got one speaker back up but the other is refusing to connect so it is obviously fixed. Just have to keep trying.

Due to the AMS outage I lost Alexa on my Move2. That was pretty good considering I have seven (7) Sonos rooms with Alexa enabled. I didn’t have to do anything with the Alexa app. However to get Alexa back onto my Move2 I removed the service and set it up again. It took a bit longer than normal but it’s back. Bottom-line in my case was to remove Alexa from the Move2 and setup again.

Most likely, the crash has broken your device's saved authentication. You should try removing your Amazon account from Era100 and setting it up again. Alternatively, reinstall any Amazon apps or updates to restore connectivity.