Announcing ConnMan.net

This usually means your driver sucks, and the supplicant isn't able to hold a connection. The driver was likely bouncing around and failing to associate periodically.

People always complain with WEP and unencrypted networks that "it works fine with iwconfig", but for some reason not with NM. NM uses wpa_supplicant, which expects a lot more out of drivers than iwconfig does. The plain fact is that if the driver can't handle WEP or unencrypted operation with wpa_supplicant, it's broken and it needs to be fixed.

Blaming NetworkManager for that is like blaming the inability of your laptop to hibernate on the Shutdown/Sleep dialog. It's not the cause of the problem. The drivers are.

NetworkManager pushes those drivers to work better, and many many driver bugs have been fixed because NetworkManager did that. It would be great if you'd file a bug so we can track down what is the problem with your driver and fix it.