NetworkManager failing to recognize ethernet connection intermittently in F25

[stan]

This is with Fedora 25, x86_64.

I've started to have a problem sometime within the last month, where on
boot I get a message that the ethernet link is up, but when I try to
use it, sometimes it can't be accessed.  I've unloaded and reloaded the
ethernet driver, and that worked once, but not another time.  If I
power down and restart the modem and router, usually NetworkManager
will recognize the link, though sometimes this take a couple of tries. 

If I power up the modem and router, and then boot, NetworkManager
*never* recognizes the link, and I have to usually power down and power
up the modem and router to get NetworkManager to recognize the link.

Once the link is established, it works like it always has, and never
fails.

Is anyone else seeing this?  Can you think of any reason this would
start happening barring a bug in NetworkManager?

[Joe Zeff]

On 01/05/2017 02:55 PM, stan wrote:
>  If I power up the modem and router, and then boot, NetworkManager
>  *never*  recognizes the link, and I have to usually power down and power
>  up the modem and router to get NetworkManager to recognize the link. 
If you're using a router, I presume that you have more than one computer 
using that modem.  Do any of them have this difficulty?  If not, we can 
eliminate them as a possible source of the trouble.

[stan]

On Thu, 5 Jan 2017 15:01:04 -0800
Joe Zeff <joe(a)zeff.us&gt; wrote:

>  On 01/05/2017 02:55 PM, stan wrote:
>  > If I power up the modem and router, and then boot, NetworkManager
>  > *never*  recognizes the link, and I have to usually power down and
>  > power up the modem and router to get NetworkManager to recognize
>  > the link.  
>  
>  If you're using a router, I presume that you have more than one
>  computer using that modem.  Do any of them have this difficulty?  If
>  not, we can eliminate them as a possible source of the trouble. 
No, just paranoid.  I use it as another layer of security between my pc
and the web.  But your suggestion leads to an interesting test I can
do.  I have rawhide installed and I haven't seen this behavior there,
though I don't boot it as frequently.  I'll watch for it, or even try
booting rawhide several times just to see if it occurs.

Thanks.

[Samuel Sieb]

On 01/05/2017 02:55 PM, stan wrote:
>  If I power up the modem and router, and then boot, NetworkManager
>  *never* recognizes the link, and I have to usually power down and power
>  up the modem and router to get NetworkManager to recognize the link.
>  
Does just unplugging and replugging the ethernet cable fix it?  When 
it's not working, what does "ethtool <interface>" show you? (e.g. 
ethtool eth0)  Does it show that the link is up or down?  Try running 
"journalctl -b" and see if there's any useful information there.

[stan]

On Thu, 5 Jan 2017 15:13:11 -0800
Samuel Sieb <samuel(a)sieb.net&gt; wrote:

>  On 01/05/2017 02:55 PM, stan wrote:
>  > If I power up the modem and router, and then boot, NetworkManager
>  > *never* recognizes the link, and I have to usually power down and
>  > power up the modem and router to get NetworkManager to recognize
>  > the link. 
>  Does just unplugging and replugging the ethernet cable fix it?  When 
>  it's not working, what does "ethtool <interface>" show you? (e.g. 
>  ethtool eth0)  Does it show that the link is up or down?  Try running 
>  "journalctl -b" and see if there's any useful information there. 
All good suggestions.  I'll try them the next time this happens.

Thanks.

NetworkManager failing to recognize ethernet connection intermittently in F25 SOLVED, sort of

[stan]

On Thu, 5 Jan 2017 15:55:29 -0700
stan <stanl-fedorauser(a)vfemail.net&gt; wrote:

>  I've started to have a problem sometime within the last month,
> where
>  on boot I get a message that the ethernet link is up, but when I try
>  to use it, sometimes it can't be accessed. 
Update - Using Joe and Samuel's suggestions, I booted rawhide and
found that it did not have the problem.  I then looked at journalctl -b
to see how the network aspects of boot differed from f25.  I found that
there was an extra stop and start of NetworkManager.  This triggered my
memory, and I remembered that a long time ago (on different hardware) I
had a problem with NetworkManager and created an rc.local file
in /etc/rc.d with the command 
systemd restart NetworkManager
in it to solve a similar problem.  This was in the rawhide system (it
has been rawhide for quite some time, just continuously bypassing
release status).  I moved it over to the F25 system, and voila, the
problem went away.

The F25 system was installed using BFO when it was still rawhide, and
I didn't completely copy all the little fixes and tweaks I usually do.
It's strange that NetworkManager would suddenly start having a problem,
but it is probably another component change that led to a race, that
NetworkManager loses.

Another anomaly is that I tried a 
systemctl restart NetworkManager 
as root to fix the issue when it happened on the F25 system.  And it
didn't work.  I stopped it, and started it, too.  Also failed.  The
journalctl -b on F25 seemed to show that the network was successfully
started, even though NetworkManager considered it unavailable.

If I feel ambitious, I'll remove the workaround and try to trace the
problem to its source.

NetworkManager failing to recognize ethernet connection intermittently in F25 SOLVED, sort of

[stan]

On Fri, 6 Jan 2017 11:35:37 -0700
stan <stanl-fedorauser(a)vfemail.net&gt; wrote:

>  an rc.local file in /etc/rc.d with the command 
>  systemd restart NetworkManager 
This is wrong.

Actual command was
/usr/bin/systemctl restart NetworkManager

journalctl -b showed 
[systemd] stopping NetworkManager
which is where I probably derived the error from.