2.4ghz network not working on fire TV sticks after the last upgrade.

The 2.4ghz network worked fine with all my firesticks before the upgrade to 5.0.5.1, now none of them will work on that network. Tried a firestick that wasn't upgraded, it still works fine. What gives? I've tried resetting the sticks, resetting my router, forgetting the network, nothing works. It connects and then disconnects over and over.