[Pkg-utopia-maintainers] Bug#943750: network-manager: wifi hotspot changes frequency and network connection breaks down

[Malte Schmidt-Tychsen]

Package: network-manager
Version: 1.14.6-2
Severity: wishlist

Hi there,

When I sit on a train and that train moves through densely populated 
areas, I lose connection to the wifi hotspot in that the pings stop, but 
network manager believes the connection is still working and shows 
everything as connected.

I believe this may be related to the wifi hotspot changing wifi channels 
trying to avoid interference of other networks in the area. In those 
densely populated areas a network scan will reveal 40 or more wifi 
networks. Sometimes it works and the laptop keeps the connection through 
a channel change. The pings will cease for up to five seconds and 
continue. But sometimes the network connection will not reestablish. I 
have also seen a channel change in the log files while the connection 
has already ceased to work and it still won't come back. I have not 
found much in the system log that would help me here. The only messages 
that occur around the times of the issue I found are these:

wpa_supplicant[6181]: wlp2s0: CTRL-EVENT-SIGNAL-CHANGE above=1 
signal=-30 noise=9999 txrate=130000

wpa_supplicant[6181]: wlp2s0: CTRL-EVENT-CHANNEL-SWITCH freq=2442 
ht_enabled=0 ch_offset=0 ch_width=20 MHz (no HT) cf1=2442 cf2=0

In fact, the following four lines appeared back to back in my logfile 
right before I lost connection:

Okt 29 05:51:38 debian wpa_supplicant[6181]: wlp2s0: 
CTRL-EVENT-CHANNEL-SWITCH freq=2442 ht_enabled=1 ch_offset=0 ch_width=20 
MHz cf1=2442 cf2=0

Okt 29 05:52:45 debian wpa_supplicant[6181]: wlp2s0: 
CTRL-EVENT-CHANNEL-SWITCH freq=2457 ht_enabled=1 ch_offset=0 ch_width=20 
MHz cf1=2457 cf2=0

Okt 29 05:53:09 debian wpa_supplicant[6181]: wlp2s0: 
CTRL-EVENT-CHANNEL-SWITCH freq=2442 ht_enabled=1 ch_offset=0 ch_width=20 
MHz cf1=2442 cf2=0

Okt 29 05:53:21 debian wpa_supplicant[6181]: wlp2s0: 
CTRL-EVENT-CHANNEL-SWITCH freq=2457 ht_enabled=1 ch_offset=0 ch_width=20 
MHz cf1=2457 cf2=0

If someone could point me towards more comprehensive log files I could 
post their contents.


I use the following:

- Dell E7450
- Intel Corporation Wireless 7265
- firmware-iwlwifi 20190717-1
- linux-image-4.19.0-6-amd64

- Google Pixel 3 Wifi Hotspot

I have been having the issue described before I got Debian 10 Buster.

Please also note that this issue did not occur with other phones used as 
hotspots. And this issue is also not limited to Debian or this laptop. 
Older devices connected to the same hotspot also seem to have issues 
staying connected during the same time. OTOH

I raised this issue with Google in the appropriate forum [1] as well as 
on XDA-Developers as well as a feedback on the phone but have received 
no response as of now. And I suspect I won't. As far as I understand 
Google will use machine learning to analyze incoming reports and only 
follow up with human readers if an issue reaches a threshhold and enough 
users are reporting it. But this could also be an expected behavior on 
newer wifi hotspots and crop up more often over time.

[1] https://support.google.com/pixelphone/thread/14799895?hl=en

Thx!

Malte