[GTALUG] Network disabled on PC after last update

[sciguy]

To recap, I have had problems with connecting my computer to the 
immediate network (let alone the internet). It is dual-boot, and Windows 
10 connects perfectly. Same hardware.

I have recently had time to examine /var/log/syslog, and I have made a 
pastebin of just the messages from NetworkManager.

https://pastebin.com/CbfnANpU

Here are some key lines that got my attention:

Apr 30 09:32:43 rivendell NetworkManager[2015]: <info>  
[1619789563.0888] device (lo): carrier: link connected
Apr 30 09:32:43 rivendell NetworkManager[2015]: <info>  
[1619789563.0890] manager: (lo): new Generic device 
(/org/freedesktop/NetworkManager/Devices/1)
Apr 30 09:32:43 rivendell NetworkManager[2015]: <info>  
[1619789563.0896] manager: (eno1): new Ethernet device 
(/org/freedesktop/NetworkManager/Devices/2)
Apr 30 09:32:43 rivendell NetworkManager[2015]: <info>  
[1619789563.5762] settings: (eno1): created default wired connection 
'Wired connection 1'
Apr 30 09:32:43 rivendell NetworkManager[2015]: <info>  
[1619789563.6633] device (eno1): state change: unmanaged -> unavailable 
(reason 'managed', sys-iface-state: 'external')
Apr 30 09:32:43 rivendell NetworkManager[2015]: <warn>  
[1619789563.9481] Error: failed to open /run/network/ifstate

It then tries again several times. If I interpret this correctly, tt 
seems to make a connecion, then by the fifth message there is a "state 
change" to "unmanaged". Any ideas as to what would cause this?

Paul

On 2021-04-18 16:57, sciguy wrote:
> Thanks a lot, Dave!
> 
> Paul
> 
> On 2021-04-18 12:47, David Collier-Brown via talk wrote:
>> On 2021-04-18 12:20 p.m., sciguy via talk wrote:
>> 
>>> I have a desktop computer that dual boots into Ubuntu Studio and 
>>> Windows 10. It is connected to the internet using a cat-5 cable to my 
>>> router.
>>> 
>>> After the last update and rebooting, it turns out that I no longer 
>>> have ethernet on Linux. This is not true on Windows, as I am writing 
>>> you this email from the same computer.
>>> 
>>> I strongly suspect that there is an update issue that is disabling 
>>> ethernet on Linux. Right now, my computer is in splendid isolation 
>>> from the rest of the world. I can't even see computer resources from 
>>> other computers in my apartment. I also can't see the router itself 
>>> through my browser.
>>> 
>>> Any ideas as to what to do next to diagnose the problem?
>> 
>> I'd start with the network manger GUI, see if you can see anything
>> obvious there, and if not, start debugging from the command-line.
>> 
>> In a previous life, I found the instructions for disabling network
>> manager contained a lot of useful information.
>> 
>> If you take that route, use script(1) and a notepad to carefully
>> record your steps, as a lot of networking stuff is sensitive to the
>> order you do things in, and you want to make a good map of where you
>> went, for the time when you want to undo the changes you made.
>> 
>> Oh, and make a backup of your home directory if you haven't already
>> 
>> --dave