Re: Conectivity loss because gateway's arp entry is incomplete
2020. 03. 04. 0:34 keltezéssel, Miguel A. Vallejo írta:
> Hello!
>
> Diagnosing one of my several problems with WiFi in Debian I found a
> problem this time not related to the WiFi connection itself, but I
> don't know how to get the culprit... Anyone can point me in the right
> direction?
>
> Symptoms: From time to time I lost Internet connection for a period of
> about 5 to 30 minutes. It happens at least two or three times a day.
>
> Setup: Desktop computer (192.168.1.2) running Debian Buster amd64 with
> current kernel 4.19.98-1 connected via WiFi to router / gateway
> (192.168.1.1). Wifi Adapter is MT7612U from Mediatek.
>
> While connection is lost:
>
> - I can launch wavemon and I can confirm the WiFi adapter is still
> connected and sending / receiving packets and beacons.
>
> - Arp command shows the gateway HWaddress as incomplete.
>
> - Launching Wireshark in the desktop computer I can see incoming
> packets from other devices, but I can also see a "Who has 192.168.1.1?
> Tell 192.168.1.2" ARP requests from my desktop every second. At first
> glance it seems the gateway isn't responding to my arp requests,
> but...
>
> - I can see arp queries from the gateway to my desktop, and I can see
> the responses, but they seem they never reach the gateway.
>
> - Forcing network activity with my smartphone, I can see also arp
> requests from the smartphone answered by the desktop, but a ping from
> the smartphone to the desktop machine gives no response. Of course the
> phone can use internet without any problem using the same gateway.
>
> - If I unplug and replug the WiFi adapter everything works again. If I
> left the WiFi adapter plugged, eventually I get an arp response from
> the gateway, and everything works normally again. This may take up to
> 20-30 minutes. Only once the wifi connection crashed after several
> minutes.
>
> It seems that when I lost connectivity I can't sent arp messages but I
> can receive them. They are sent, I can see them with Wireshark, but it
> seems they will never get outside the machine. I searched for known
> bugs but I wasn't able to find anything, only a message from an Ubuntu
> user aparently having the same problem, but with a different WiFi
> adapter and kernel version (4.18 I think):
>
> https://askubuntu.com/questions/1122683/no-internet-access-after-random-intervals-in-ubuntu-18-04-2-lts
>
> The problem is now I don't know how to get the culprit of this bug. Is
> the kernel? Is the Mediatek kernel module?
>
> Any help will be appreciated.
>
Try to add your gateway arp with static arp entry and check whether the
problem persists.
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