Re: wifi permanently switching between 2.4 and 5 GHz

[Greg Oliver <oliver greg gmail com>]

On Tue, Aug 14, 2018 at 2:24 PM "Jürgen Bausa" <Juergen Bausa web de> wrote:

I have a Xiaomi Air 12 Laptop (Intel Core m3-7Y30, Network controller: Intel Corporation Wireless 8260 
(rev 3a)). I use debian Stretch (linux 4.9.0-7-amd64) with KDE and Network-Mananger (1.6.2-3). 

 

Until now, wifi worked fine. However, after I exchanged my router (which had only 2.4 GHz) against a
newer model that has both 2.4 and 5 GHz (both frequencies with the same ssid), I experienced the 
following problem: The computer switches permanently between both frequencies. This happens approximately 
every 2 minutes. In /var/log/messages I find the following:

 

Aug 12 14:45:12 lina kernel: [ 2256.208621] wlp1s0: disconnect from AP xx:xx:xx:xx:xx:xx for new auth to yy:yy:yy:yy:yy:yy
Aug 12 14:45:12 lina kernel: [ 2256.213032] wlp1s0: authenticate with yy:yy:yy:yy:yy:yy
Aug 12 14:45:12 lina kernel: [ 2256.223163] wlp1s0: send auth to yy:yy:yy:yy:yy:yy (try 1/3)
Aug 12 14:45:12 lina NetworkManager[564]: <info>  [1534077912.6843] device (wlp1s0): supplicant interface state: completed -> authenticating
Aug 12 14:45:12 lina kernel: [ 2256.228342] wlp1s0: authenticated
Aug 12 14:45:12 lina kernel: [ 2256.229481] wlp1s0: associate with yy:yy:yy:yy:yy:yy (try 1/3)
Aug 12 14:45:12 lina kernel: [ 2256.230627] wlp1s0: RX AssocResp from yy:yy:yy:yy:yy:yy (capab=0x11 status=0 aid=1)
Aug 12 14:45:12 lina kernel: [ 2256.231932] wlp1s0: associated
Aug 12 14:45:12 lina NetworkManager[564]: <info>  [1534077912.6931] device (wlp1s0): supplicant interface state: authenticating -> associated
Aug 12 14:45:12 lina NetworkManager[564]: <info>  [1534077912.7338] device (wlp1s0): supplicant interface state: associated -> 4-way handshake
Aug 12 14:45:12 lina NetworkManager[564]: <info>  [1534077912.7414] device (wlp1s0): supplicant interface state: 4-way handshake -> completed

 

where xx:xx:xx:xx:xx:xx the MAC of 2.4 and yy:yy:yy:yy:yy:yy the MAC of 5 GHz net is.

 

However, this happens not at all places in my house. Near the router, 5 GHz is much stronger than 2.4 Ghz 
and the system keeps th 5 GHz net. But in the living room, both nets have nearly the same strength and the 
systems switches all the time.

 

I found a lot of description of exactly this problem, but no solution on the net. See e.g.
https://forum.manjaro.org/t/frequent-wifi-disconnect/12211
https://jeremyfelt.com/2017/01/02/things-i-learned-or-broke-while-trying-to-fix-my-wireless-in-ubuntu-16-10/
https://www.archybold.com/blog/post/intermittent-connectionhigh-packet-loss-intel-wireless-driver-iwlwifi-ubuntu-linux-networkmanager

 

I think there should be some treshold that avoids switching between nets based on small fluctiations. But 
where can I set this treshold. And is the switching caused by NM or by the driver? As the bugreports 
mention different adapters, I think its not driver specific.

 

Any hints welcome.

 

juergen

This is a long time nuisance of mine with NM and wpa-supplicant in Linux.  I just set the BSSID in NM to the MAC of the 5Ghz chip on the AP

.  This also keeps it from scanning into 2.4 and causing 10 seconds drop outs.

Unfortunately, I do not think a better way exists in Linux, which is unfortunate for us desktop users.  IMO, it is a major flaw that needs to be reworked ground up - it only happens on Linux (compared to MacOS and Windows on the same AP anyway - I have never run *BSD variants on a desktop machine).

 

-

Greg