Microsoft is happy that this issue is now completely resolved after a period of monitoring showed no further issues. Preliminary investigation by Microsoft indicated that a routing change made by Microsoft caused some internet traffic to fail before it reached Microsoft application servers. That change was rolled back and service was restored.
Microsoft Current status: We’ve identified that a recent networking update may have caused user traffic coming from the internet to fail intermittently before reaching Microsoft 365 services. We’ve reverted this update and are seeing some initial signs of mitigation. We’re continuing to validate the cause of the problem while we monitor the environment for service recovery
Microsoft Current status: We’ve determined that users may experience intermittent access issues with the Microsoft 365 Admin Center, Exchange Online, SharePoint Online, Microsoft Teams, Skype for Business, and Yammer at this time. We’re continuing our investigation into the root cause and we’ll provide more information when we’ve isolated the root cause