A few people have noticed their AT&T branded Netgear Nighthawk mobile hotspots recently prompting to install a mandatory firmware update from AT&T - version: NTG9X50C_12.05.05.12
This seems to be a very minor bug fix release, and it is perhaps caught in a time warp - AT&T's page on the firmware says that it was originally from December 19, 2018.
Jan. 21, 2020 Update: This new release has an Ethernet bug that is preventing some users from utilizing the Ethernet port. Netgear is aware of the issue and is working on a fix.
Feb. 12, 2020 Update: AT&T pushed version 12.05.05.14 to fix this bug.
The "What's New" listed is relatively insignificant:
What's new: Ethernet to LTE Failover (Always-On Wi-Fi) feature, SMS Alert feature (disabled via configuration), Support for disabling factory reset button
Confusing things - in November 2019 Netgear released an update labeled as 12.06.08.00 for the Nighthawk MR1100 that includes a fix for reboots when running without a battery installed. This update is for the non-AT&T branded unlocked Nighthawk models, and is newer than what AT&T has now released.
Perhaps AT&T pushed the old minor 12.05.05.12 to lay the groundwork for an imminent official update to 12.06.08.
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[…] appears to be a relatively minor update that addresses some bugs that were discovered in the recently released 12.05.05.12 version that caused disconnects and issues with the Ethernet port. The change from the previous update […]