[DeKuns]

Mine is Kindle DX Graphite. 3G is five bars, I can browse the Kindle store. So 3G is working. The linkage to and from Amazon server is broken after a factory reset.

If you happen still has Gen 1-2 that still registered and connect to Amazon, then do not factory reset. Deregister from the device will not work. I never try it because my Kindle has been factory reset but to smoothly transfer registration of these Kindle might be possible by asking Amazon CS to move it from one account to another by chat or phone as long as it is not factory reset recently.

Let Amazon solved this either by fixing or announce EoL of Gen 1-2!

What I do know from the debug file that they asked me to produce from the device and sent it to them is that:
1. Once factory reset, "/var/local/java/prefs/certs" is empty.
2. When Kindle device tried to register, it will check somekind of DRM signature at this location, /var/local/java/prefs/acsr. It will not find it after factory reset.
3. Because the file is not found in the Kindle device, it asked this from Amazon server at "fras.amazon.com". At this point the Kindle device will get "file not found" from the server.

This is happen even after installing 2016 Kindle service update. I just hope my opinion is wrong and Amazon technician only by their ignorance move the what @knc1 called "general certificate" to other location. If the second one that happen, then Amazon better update their 2016 Kindle security update to point this new location.