Wlan permanent switching between 2.4 and 5.1 GHz, how to stop this

English Network/Internet
1

Hi,

Thinkpad t460p

at home I have a tp link router that supports 2 frequencies
and my notebook can also do both

the problem is, my wlan disconnects and reconnects very often,
and after reconnect it always has the different frequency than before
so I guess it does switching the frequency, but why?

Can I pin the WLan, networkmanager, to one frequency?
These reconnects are super annoying


/usr/sbin/hwinfo --wlan
17: PCI 300.0: 0282 WLAN controller                             
  [Created at pci.378]
  Unique ID: y9sn._1zYJqZDqT9
  Parent ID: z8Q3.NMIGalQjZq7
  SysFS ID: /devices/pci0000:00/0000:00:1c.0/0000:03:00.0
  SysFS BusID: 0000:03:00.0
  Hardware Class: network
  Model: "Intel Wireless 8260"
  Vendor: pci 0x8086 "Intel Corporation"
  Device: pci 0x24f3 "Wireless 8260"
  SubVendor: pci 0x8086 "Intel Corporation"
  SubDevice: pci 0x0130 
  Revision: 0x3a
  Driver: "iwlwifi"
  Driver Modules: "iwlwifi"
  Device File: wlan0
  Features: WLAN
  Memory Range: 0xf2100000-0xf2101fff (rw,non-prefetchable)
  IRQ: 129 (no events)
  HW Address: e4:b3:18:7b:3a:b8
  Permanent HW Address: e4:b3:18:7b:3a:b8
  Link detected: yes
  WLAN channels: 1 2 3 4 5 6 7 8 9 10 11 12 13 36 40 44 48 52 56 60 64 100 104 108 112 116 120 124 128 132 136 140
  WLAN frequencies: 2.412 2.417 2.422 2.427 2.432 2.437 2.442 2.447 2.452 2.457 2.462 2.467 2.472 5.18 5.2 5.22 5.24 5.26 5.28 5.3 5.32 5.5 5.52 5.54 5.56 5.58 5.6 5.62 5.64 5.66 5.68 5.7
  WLAN encryption modes: WEP40 WEP104 TKIP CCMP
  WLAN authentication modes: open sharedkey wpa-psk wpa-eap
  Module Alias: "pci:v00008086d000024F3sv00008086sd00000130bc02sc80i00"
  Driver Info #0:
    Driver Status: iwlwifi is active
    Driver Activation Cmd: "modprobe iwlwifi"
  Config Status: cfg=no, avail=yes, need=no, active=unknown
  Attached to: #9 (PCI bridge)
2

Hi
That’s all controlled by the router (probably set to auto) as it will search for the least channel that has interference. I would guess that’s why it drops the connection as the router is possibly bouncing around. In the router you should be able to do a wireless scan and find a channel that’s free and set the router to use that. If you can change the aerial position this may also help with channel interference.

3

thanks for the info, I found 2 settings, channel with and channel
I do not know what to take for channel with, it’s 20/40 for 2.4ghz and 20/40/80 for 5 ghz
nothing to scan, but I chosen the first, lowest, channel
the router is a tp link archer c9

however, i still wonder if its possible to pin the wlan to one of both frequencies on the notebook, or is this also a router decision, what to assign?

4

Hi
The router sets the channel, select on or the other 2.4 or 5…

Are your wifi cards 1X1? If so set the bandwidth to 40 on 2.4GHz and 40 or 80 for 5.0Ghz that should get full speed

5

still disconnects, I do not believe that this is just the router,
no problems on other notebooks with other os and distribution
strange

and it again hopped from 5.1 to 2.4 GHz, I think this is the OS on the notebook doing so

6

all 6 minutes change from one frequency to an other


ec 19 19:17:38 t460p.suse NetworkManager[1076]: <info>  (wlan0): roamed from BSSID 50:C7:BF:18:FA:17 (network_name) to (none) ((none))
Dec 19 19:17:38 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: completed -> authenticating
Dec 19 19:17:38 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: authenticating -> associated
Dec 19 19:17:38 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: associated -> 4-way handshake
Dec 19 19:17:38 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: 4-way handshake -> completed
Dec 19 19:17:38 t460p.suse NetworkManager[1076]: <info>  (wlan0): roamed from BSSID (none) ((none)) to 50:C7:BF:18:FA:16 (network_name)
Dec 19 19:23:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): roamed from BSSID 50:C7:BF:18:FA:16 (network_name) to (none) ((none))
Dec 19 19:23:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: completed -> authenticating
Dec 19 19:23:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: authenticating -> associating
Dec 19 19:23:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: associating -> 4-way handshake
Dec 19 19:23:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: 4-way handshake -> completed
Dec 19 19:23:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): roamed from BSSID (none) ((none)) to 50:C7:BF:18:FA:17 (network_name)
Dec 19 19:29:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): roamed from BSSID 50:C7:BF:18:FA:17 (network_name) to (none) ((none))
Dec 19 19:29:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: completed -> authenticating
Dec 19 19:29:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: authenticating -> associated
Dec 19 19:29:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: associated -> 4-way handshake
Dec 19 19:29:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: 4-way handshake -> completed
Dec 19 19:29:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): roamed from BSSID (none) ((none)) to 50:C7:BF:18:FA:16 (network_name)
Dec 19 19:31:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): roamed from BSSID 50:C7:BF:18:FA:16 (network_name) to (none) ((none))
Dec 19 19:31:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: completed -> authenticating
Dec 19 19:31:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: authenticating -> associating
Dec 19 19:31:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: associating -> associated
Dec 19 19:31:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: associated -> 4-way handshake
Dec 19 19:31:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: 4-way handshake -> completed
Dec 19 19:31:35 t460p.suse NetworkManager[1076]: <info>  (wlan0): roamed from BSSID (none) ((none)) to 50:C7:BF:18:FA:17 (network_name)
Dec 19 19:37:38 t460p.suse NetworkManager[1076]: <info>  (wlan0): roamed from BSSID 50:C7:BF:18:FA:17 (network_name) to (none) ((none))
Dec 19 19:37:38 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: completed -> authenticating
Dec 19 19:37:38 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: authenticating -> associated
Dec 19 19:37:38 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: associated -> 4-way handshake
Dec 19 19:37:38 t460p.suse NetworkManager[1076]: <info>  (wlan0): supplicant interface state: 4-way handshake -> completed
Dec 19 19:37:38 t460p.suse NetworkManager[1076]: <info>  (wlan0): roamed from BSSID (none) ((none)) to 50:C7:BF:18:FA:16 (network_name)


t460p:~ # /usr/sbin/iwconfig
lo        no wireless extensions.

wlan0     IEEE 802.11abgn  ESSID:"network_name"  
          Mode:Managed  Frequency:2.412 GHz  Access Point: 50:C7:BF:18:FA:17   
          Bit Rate=144.4 Mb/s   Tx-Power=22 dBm   
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality=61/70  Signal level=-49 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:3   Missed beacon:0

eth0      no wireless extensions.

t460p:~ # /usr/sbin/iwconfig
lo        no wireless extensions.

wlan0     IEEE 802.11abgn  ESSID:"network_name"  
          Mode:Managed  Frequency:5.18 GHz  Access Point: 50:C7:BF:18:FA:16   
          Bit Rate=144.4 Mb/s   Tx-Power=22 dBm   
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality=61/70  Signal level=-49 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

eth0      no wireless extensions.

this shall be done from the router? I do not think so

7

You can prevent unwanted roaming by editing your connection profile and locking it to a particular BSSID. (I note from the output you posted that the BSSID for the 2.412 GHz AP is 50:C7:BF:18:FA:17 for example, while the 5GHz AP is identified associated with 50:C7:BF:18:FA:16.)

https://blogs.gnome.org/dcbw/2016/05/16/networkmanager-and-wifi-scans/

Hope this helps.

8

Hi
Your using network manager? Try setting the BSSID to either of the mac addresses for the AP depending on what frequency you want to use.

9

thanks deano_ferrari and also malcolmlewis

this looks very promising, have now a stable connections since more than half an hour!