On Sat, 27 Feb 2021 at 17:59, Doug H. <fedoraproject.org@wombatz.com> wrote:
On Sat, Feb 27, 2021, at 1:36 PM, Cameron Simpson wrote:
> On 27Feb2021 09:50, Doug H. <fedoraproject.org@wombatz.com> wrote:
> >I am having an odd problem with my ethernet port. I assume this came
> >with a dnf update but that was some weeks ago so I can't help figure
> >out what update might have done it. When first discovered I think I
> >found that booting from an older kernel did not fix it. I assume that
> >the physical interface is not the problem since a physical "bounce"
> >always fixes it and it shows no other problems. To explain that...
> [...]
> >The simple fix is to physically unplug and replug the cable. When it is
> >not working (each reboot) there are not lights on. The physical
> >"bounce" lights up the LEDs and it comes right up.
> >
> >So, I am asking for something to add to rc.local that does the same
> >thing.
>
> Have you tried something as simple as:
>
>     ifconfig enp5s0 down
>     sleep 2
>     ifconfig enp5s0 up


Yup, I should have noted the various stuff I have tried. A couple of times now I have rebooted to create the issue and then pounded on the interface with no luck. I then just unclip/pull/push the cord and it comes up like magic.
Have you inspected the jack (uses a magnifier in good light) and tried a different cable?   Once corrosion starts connections can go bad but will start to work after a replug cycle.    You can buy contact enhancer that can often help in such cases.
 

After posting this I installed an old PCI ether card to get around the issue. The only trouble there is that the card does not seem to support "Wake on LAN" which is annoying but I think I can live with that.

Another note that I should have included is that this *is* a very old box. It will be 12 years old sometime this year (October I think). And this is the onboard LAN, so maybe it *is* something physical. It just seems odd that it works without issue once it is "bounced" to the working state.

At my work we once had a PC whose networking seemed fine until we needed PCNFS, which refused to work.  The vendor's diagnostics didn't indicate any problem, but when I pulled the card there were obvious burned components.    Your time might be better spent getting a modern replacement, but I realize there are use cases where a modern replacement can be difficult.
--
George N. White III