Connectivity appears to have fully restored and iOS push notifications are sending.
Posted Nov 17, 2015 - 23:20 EST
Update
We have tested a variety of cloud providers in different data centers and cannot connect to APNs from them either. Apple's Developer Status page is not loading, which further leads us to believe it an issue on Apple's end. We will remain on top of this and all queued messages will be sent once connectivity is restored.
Posted Nov 17, 2015 - 22:53 EST
Investigating
As of a few minutes ago, our servers have been experiencing issues connecting to the Apple Push Notification Services (APNs). We are also seeing intermittent connectivity issues to APNs from servers outside our environment, and The Internet Health Report (http://internethealthreport.com/) shows a critical issue affecting the Tier 1 networks Level 3 and Savvis, which may be to blame. iOS Push Notifications are currently being queued and will be sent when the connectivity resumes. Our team is continuing to investigate, but it appears to be an issue with APNs connectivity.