When networkmanager starts, it detect incorrectly link state of network card. It assumes that link is in connected state even if it isn't. This lead into problems when card get connected into network, because dhcp configuration cannot be got from network.
Please see attached log.
I have tested this with 2 different types of ethernet cards (rtl8139, rtl8169), and on x86 and amd64 architectures.
Created attachment 110968 [details]
Log from startup of networkmanager
If this is happening it is due to the drivers reporting link state when there is no link. Does this still exist with latest kernels?
I'm having exactly the same issue.