I've been having problems with NetworkManager dhcp on my Fedora27 Workstation (desktop, wired).. Note, because I'm using VMs on that workstation, the interface is a bridge (br0 with slave eno1).
What seems to happen is this:
Workstation wakes up from sleeping, reactivates connection.
dhclient issues 4 DHCPDISCOVER tries, none of which get a response.
the interface state changes "unknown-->timeout->done", and the DHCPv4 transaction is cancelled.
A restart is scheduled for 120 seconds later.
The restart 120 seconds later succeeds with DHCPDISCOVER, DHCPREQUEST, DHCPOFFER, DHCPACK.
All the other machines served by my DHCP server have no problems at all, however, they are MacBooks, various storage servers, and RaspberryPis.
It seems to be that NetworkManager somehow interferes with the DHCPDISCOVER after the workstation wakes up.
The attached log file shows this sequence of events.
(I'm wondering if there is a timing issue because the first dhclient call is issued when eno1 is in the "unavailable" state, and before it is captured as a slave to br0)
Attachment:
nm-weirdness.log
Description: Text Data