On Wed, 1 Jan 2020 at 23:21, Robert G (Doc) Savage via users <users@lists.fedoraproject.org> wrote:
It would seem that "something" happened to the file(s) that provide
RJ45 Ethernet connectivity maybe as far back as F29. I can get a WiFi
connection, but not an RJ45 eth0 DHCP connection. This happens in my
home and at a nearby computer store, so it's not my DHCP server.

Use the "ip" command to see the status of your network devices.

There have been problems with the way network devices are powered
up and down due to changes in the kernel power management.  If you
goggle your ethernet device or the model of your system you may find
the problem has already been addressed. 

If you think this is a power management problem, look for ASMP (Active
State Power Management) in dmesg.  You can install the fwts package
with dnf and run "$ sudo fwts aspm".


When booted up to WiFi, connecting an RJ45 Ethernet cable shuts down
the existing WiFi port (normal), but never comes up with a DHCP address
for the eth0 port. The network icon just loops forever. When I
disconnect the RJ45 cable, WiFi connectivity resumes after 5-10
seconds.

Does ethernet work if you boot with the cable connected (and wifi
disabled if your system has an external switch)?
 

The problem has persisted since upgrades to both F30 and F31. I'm
guessing the best way to fix the problem is a fresh install of whatever
packages provide eth0 connectivity. I'm at a loss to know what those
packages are, and if there are any hidden potholes/landmines with
simply using dnf to first remove then to install them from scratch.

If you have an older system you may be missing a binary blob, in which
case dnf won't help.

I have semi-retired 10-year old desktop running Linux Mint.   In the last year
or so the linux kernel people did a purge of unmaintained, unsupported binary
blobs (including the tigon3 ethernet hardware in my system).   This was
due to security concerns as well as the extra workload for kernel maintainers.

There was a line in dmesg giving the name of the missing file.  I had to
find the missing driver file and put it in the appropriate location.  Check
your ethernet device and the status of the drivers on the vendor's site.  
Fedora appears to have the binary blob for my hardware, as
I was able to install Fedora 30 from a live USB and upgrade to 31.


If it matters, I'm using the mate v1.22.2 desktop. Here are all the
*mate* packages I have installed:

# rpm -qa | grep mate | sort  [...]

Some detailed guideance would be much appreciated.

Incidentally, I have appended " net.ifnames=0" to the
GRUB_CMDLINE_LINUX= line and rebuilt the initramfs to revert back to
classic eth0 nomenclature for the RJ45 Ethernet port. I can't stand the
new naming convention. :-)

Does ethernet work if you revert the changes (or did it  work before the
changes)?
 

--
George N. White III