The wireless card of the weather station computer in the shed is dual-band
but with only a 2.4 GHz capable antenna. Since the house access-point is
configured to support both 2.4 GHz and 5 GHz channels the system sometimes
selects the 5 GHz access and keeps having serious packet loss. I looked
at ways to convince the driver to select 2.4 GHz channels only but found
none, but then I found out
wpa_supplicant can do this. But I
configure
wpa_supplicant through wpa-* options in
/etc/network/interfaces
so I had to find out how to configure it using those. The manpages for the
interfaces file is very limited on the wpa-* options, but I found an explanation
that a lot of wpa_supplicant options are supported, including the one to
select frequencies. The sneaky part is that the option in
wpa_supplicant.conf
is
freq_list and the option in
/etc/network/interfaces is
wpa-freq-list.
A rather complete list can be found at
Where can I find a full list of wpa-* options for the interfaces file? - superuser.com.
So now I have in
/etc/network/interfaces:
auto wlan0
iface wlan0 inet dhcp
wpa-ssid default
wpa-psk VerySecret
wpa-freq-list 2412 2417 2422 2427 2432 2437 2442 2452 2457 2462 2467 2472
The ideal solution is to order a dual-band (2.4 GHz and 5 GHz) antenna.
Update:
Noticeable absent are channels 12 and 13 which are available for regulatory
domain NL but are not listed when I ask the driver for available channels:
koos@ritchie:~$ /sbin/iwlist wlan0 chann
wlan0 19 channels in total; available frequencies :
Channel 01 : 2.412 GHz
Channel 02 : 2.417 GHz
Channel 03 : 2.422 GHz
Channel 04 : 2.427 GHz
Channel 05 : 2.432 GHz
Channel 06 : 2.437 GHz
Channel 07 : 2.442 GHz
Channel 08 : 2.447 GHz
Channel 09 : 2.452 GHz
Channel 10 : 2.457 GHz
Channel 11 : 2.462 GHz
Channel 36 : 5.18 GHz
Channel 40 : 5.2 GHz
Channel 44 : 5.22 GHz
Channel 48 : 5.24 GHz
Channel 52 : 5.26 GHz
Channel 56 : 5.28 GHz
Channel 60 : 5.3 GHz
Channel 64 : 5.32 GHz
Current Frequency:2.462 GHz (Channel 11)
And now I wonder why those are missing.