The MB NIC randomly needs unplug/plug after boot to wake it up. I think I may have fixed it by rmmod/modprobe e1000e after I log in. I wonder if there is a kernel arg or ethtool hack to fix. Maybe my NIC is flaky. The PC is still under warranty for another week or so.

Any ideas/similar issues?

Check BIOS configuration, whether some setting can stop sleeping.

The intel nics are well supported an generally one of the better choice in linux.

Some people report that the nic speed doesn't return correctly and that seems to lock it up. Do you see any blinking lights on resume? Have you tried any other hub/switch/router? Have you double checked that you have a patch cable in instead of a cross over? Most distro's have a way to stop and start/restart networking.

I think I'd poke around more in /var logs.

As above, look at power issue like apm, acpi support and bios support.

What distro and version are you running?

There was a bug in the e1000 (1000e? e1000e? I don't remember) kernel module that would cause the NIC to lock up. I know it was in CentOS 6.5 when it was first released, and was patched within a few weeks. It was one of those problems where you would install the OS from disk, and then had to boot up the machine and IMMEDIATELY do a "yum update" to apply the patch because you only had about a minute and a half before the NIC would lock up and you had to try again. It affected a few of my systems with SuperMicro motherboards and Intel GbE NICs.

I've checked BIOS thoroughly, nothing to set, other than turn it off completely.

The strange thing is that it seems to be random. If I reboot, check eth0, and reboot again continuously, sometimes it works fine 3 times in a row, then fail a few times, then work, then fail. It just seems random.

Once it's working, it stays working, and doesn't drop out or go to sleep or anything. The rmmod/modprobe trick always gets it working properly.

Perhaps it is a bug in e1000e.ko, but I have new arch module. I've tried fiddling with the module args and none of them affect whether it starts properly.

e1000e is loaded in initrd. I'm thinking of removing it and loading it a bit later, see if that makes a difference. Maybe something else needs to set up first to be reliable.

EDIT: loading e1000e later seems to make a difference. 10 reboots now and dhcpcd is up and running all 10 times. Ah, well, there ya go. I'm glad it's not a flaky NIC, the box is quite nice otherwise.

Thank you for the replies.