Odd network behavior

[rikona]

On Tue, 01 Aug 2017 00:12:52 -0400
"Ken D'Ambrosio" <ken at jots.org> wrote:

> Based on your description, it sounds an *awful* lot like one of your 
> routers -- the one you're plugged into -- is power cycling
> occasionally. 

Agreed, it does sound like that. But I have CAT5 to router #1, and it
ONLY does this when router #2/access point is connected. Why would it
cycle only when #2 is attached? Essentially nothing is touched on #1
when I connect/disconnect #2 - it is done at the other router location.
Runs fine with #2 disconnected...

A good thought - thanks.

> I'd watch the LEDs on the router (especially when you
> lose connectivity) and see if they seem to be indicating a boot
> sequence.  If so, I'd check that the power supply and cables are
> well-plugged-in; if they are, I might consider a new router.  But
> first, I'd try a different wall power place, just for kicks.
> 
> -Ken
> 
> On 2017-08-01 00:07, rikona wrote:
> > I'm seeing some odd network behavior that I don't understand. The
> > problem started when I decided to improve the wireless coverage in
> > my house by using an extra router as second access point. Both
> > routers have the same SSID and the same encryption and password.
> > The second router has different LAN IP address, a different
> > channel[using 5 and 9], and the DHCP server is turned off in the
> > second router/access point. This second router/access point does
> > work and does extend the wireless coverage significantly, so that
> > function seems to be working.
> > 
> > But, I started noticing on my Ubuntu box that I was periodically
> > losing my network connection about every 5 to 20 minutes. The
> > connection would go down for a couple of minutes then come back up.
> > When the connection went down, all the lights next to each CAT5
> > connector would go off completely [which seemed odd], not even
> > flickering. After a minute or two the input CAT5 connector light
> > would go on, followed shortly by the rest of the CAT5 connector
> > lights, and the network would be up.
> > 
> > At first I was blaming Comcast because their local service is not at
> > all reliable, but after a day or so I began to consider that the
> > problem might be at my end. I have another router [primarily used by
> > someone else as a DMZ] ahead of both of the above routers, and that
> > DMZ connection did not seem to be going down which showed that the
> > problem was at my end and not at Comcast.
> > 
> > I thought I might get some clues by looking at syslog, which does
> > show these disconnects. The log is very large, but I'm hoping the
> > following excerpts might provide enough clues to understand what is
> > going on.
> > 
> > This snippet shows the disconnect:
> > 
> > "
> > NetworkManager[918]: <info>  [1501536278.6169] device (enp4s0): link
> > disconnected
> > NetworkManager[918]: <info>  [1501536278.6170] device (enp4s0):
> > state change: activated -> unavailable (reason 'carrier-changed')
> > [100 20 40] .....
> > NetworkManager[918]: <info>  [1501536278.6281] manager:
> > NetworkManager state is now DISCONNECTED
> > "
> > and the following snippet shows the reconnect:
> > 
> > "
> > NetworkManager[918]: <info>  [1501536319.8205] device (enp4s0): link
> > connected kernel: [2495080.876510] igb 0000:04:00.0 enp4s0: igb:
> > enp4s0 NIC Link is Up 1000 Mbps Full Duplex
> > NetworkManager[918]: <info>  [1501536319.8228] manager:
> > NetworkManager state is now CONNECTING
> > ...
> > NetworkManager[918]: <info>  [1501536319.8452] policy: set 'Wired
> > connection 1' (enp4s0) as default for IPv4 routing and DNS
> > ...
> > nmbd[1466]: [2017/07/31 14:27:07.998589,  0]
> > /source3/nmbd/nmbd_become_lmb.c:397(become_local_master_stage2)
> > nmbd[1466]:   Samba name server CHEWIE is now a local master browser
> > for workgroup FAMILY
> > "
> > NOTE - this computer IS the one that I would like to be the master
> > browser for the workgroup, so that part is working as I'd like.
> > 
> > The network then functions okay for 5 to 20 minutes, then repeats
> > the same disconnect/reconnect again and again.
> > 
> > At this point I disconnected the second router/access point and the
> > behavior changed. It no longer disconnects/reconnects, but the
> > network behavior in the Ubuntu box is different, and not what I
> > want.
> > 
> > At the next reconnect we get:
> > 
> > NetworkManager[918]: <info>  [1501536890.1845] manager:
> > NetworkManager state is now CONNECTING
> > ...
> > 
> > nmbd[1466]: [2017/07/31 14:39:06.910864,  0]
> > ../source3/nmbd/nmbd_incomingdgrams.c:304(process_local_master_announce)
> > nmbd[1466]: [a different Linux computer ] is announcing itself as a
> > local master browser for workgroup FAMILY and we think we are
> > master. Forcing election.
> > nmbd[1466]:   Samba name server CHEWIE has stopped being a local
> > master browser for workgroup FAMILY
> > 
> > [1] Now this is NOT what I want, but it is not clear to me why this
> > box has stopped being a local master browser for the workgroup. I
> > would appreciate any insights as to why that happened, and how I
> > can get the original 16.04 computer to be the master browser, and
> > stay that way.
> > 
> > [2] Also, it is not clear to me why adding the second router as an
> > access point caused the first router to periodically stop working. I
> > would also appreciate VERY MUCH any insights as to why that might
> > happen.
> > 
> > I can post the entire logs if that would be helpful, but they are
> > quite large - please let me know if I should do that.
> > 
> > Thanks for reading this...  
>