Airports and Time Capsules cannot connect to iCloud/Back to my Mac
In the last week, every single Airport device I use has been failing to allow remote access via Back to my Mac.
When you go to Airport Utility and go to the iCloud credential section and add an iCloud ID, the light goes green, indicating that the credentials check out. Then you have to restart to apply changes. After restart, the iCloud IDs all have red lights next to them, and the advisory message says "This Airport could not connect to iCloud." All other functions on the Airport work just fine... just not the Back to my Mac/iCloud ID certification.
This happens on every single Airport I come across now, a variety of models and firmwares and ISPs.
Clearly, the problem is iCloud and Back to my Mac.
I have two separate issues into Apple now, but all they say is that there is a problem with my computer that they need to investigate. That is simply not true. The problem is with iCloud and Airport devices.
This seemed to happen right after iCloud announced they had dual authentication available for certain apps, but that could just be a coincidence.
As a word of warning to users out there, I have found that if the iCloud ID settings are on an Airport device they will continue to work, but if you do ANY changes or restarts to an Airport device, then that device will shut off the MTMM/iCloud ID.