[kwlug-disc] Networking issue

[Khalid Baheyeldin]

No.
R2 does not provide any power to anything. Nothing plugged in its USB port.

On previous instances of this issue (months back), I was able to make things
work by rebooting both routers, then power cycling the Pi (which I don't
want
to do, file system corruptions and all that).

Today, I can't recover. Maybe because I messed with the arp tables?

On Mon, Aug 5, 2019 at 6:18 PM Raymond Chen <raymondchen625 at gmail.com>
wrote:

> 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
>> _______________________________________________
>> kwlug-disc mailing list
>> kwlug-disc at kwlug.org
>> http://kwlug.org/mailman/listinfo/kwlug-disc_kwlug.org
>>
>

-- 
Khalid M. Baheyeldin
2bits.com, Inc.
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