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?