[kwlug-disc] Networking issue

[Raymond Chen]

Does your R2 provide power for your Raspberry Pi? I used to have a router
behaving strangely when its USB was connected to my Raspberry Pi. I would
try unplugging all devices from R2’s USB ports and see if that works.

Raymond

On Mon, Aug 5, 2019 at 16:50 Khalid Baheyeldin <kb at 2bits.com> wrote:

> I have this rare problem that is extremely annoying when it happens.
> Basically, I have two routers. R1 is the main home router, connected
> to the internet, managing DHCP, and so on. The other router, R2, has
> no DHCP, and is simply for range, as well as a couple of RJ45 devices,
> due to proximity to those devices.
>
> Some WiFi devices that report temperature, humidity, ...etc. report
> to R2 due to better range. A Raspberry Pi is connected to R2 directly
> using RJ45. The Pi and the WiFi devices have static IPs in R1 served
> using DHCP.
>
> On rare occasions, the WiFi on R2 misbehaves. I can still ssh into the
> Pi, but the WiFi devices have trouble reporting to the Pi. The solution
> is to reboot the routers. Doing so makes WiFi more stable, but then
> the Pi is inaccessible over ssh or HTTP. I have to cycle power to the
> Pi, and I hate doing that since it may corrupt the file system on the
> SD card.
>
> Even when reboot both routers and cycle power, the Pi is not accessible
> still. Pings fail, let alone ssh. Don't know why.
>
> The only clue I can find is that when I use arp (from R1), the Flags
> column for the Pi is 0x0 while it is 0x02 for all other devices.
>
> I tried to delete the arp entry for the Pi, using this, from a Linux
> machine:
>
> arp -d 192.168.0.x
> arp -s 192.168.0.x b8:27:xx
>
> After that, I see this:
>
> Address HWtype  HWaddress           Flags Mask            Iface
> zz           ether       b8:27:xx                CM                    eth0
>
> Again, the Flags column is CM, while it is C on other devices.
>
> How can go about troubleshooting this extremely annoying problem?
>
> --
> Khalid M. Baheyeldin
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> kwlug-disc at kwlug.org
> http://kwlug.org/mailman/listinfo/kwlug-disc_kwlug.org
>
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