Dear Maintainer,

I downloaded Debian 7.7 installation image[1].

I followed the installation procedure and chose wlan0 networki interface
when asked to configure the primary network interface. Then there was no
WLAN on the list of availble networks. It appeared after I changed
channel on my AP from 13 to 1.

I suspect the reason of this problem MAY be the default regulatory
settings of wifi stack/card driver in the Linux kernel if it is prepared
for the USA where, according to Wikipedia[2], the channel may be used
only under certain conditions.

[1] debian-7.7.0-amd64-i386-netinst.iso (md5 afc576c3886f9abab9ba886c4cd51a88)
[2] https://en.wikipedia.org/wiki/List_of_WLAN_channels

... Od tej pory wszystko może się zdarzyć. Akcja toczy się...

Control: tag -1 moreinfo

The default is to use the 'world' regulatory domain, not the US domain.
This still allows scanning for and using an AP on all channels; it just
doesn't allow transmissions above channel 11 until an AP is found.

However this might be overridden based on the country setting of the
wireless network adapter.  Or a particular driver might not implement
the regulations correctly.

Please specify what wireless network adapter you are using (if it's
something built in and you don't know, lspci or lsusb will help to
identify it).

Also please provide the system log from the installer.

Ben.

That's strange, apparently the card has been prepared to be for
Australians, who can use channel 13.


It is TP-LINK TL-WN781ND using ath9k driver.


There is probablo nothing more interesting there than the above excerpty
but I am attaching it anyway.

This driver uses a table of maximum TX power per channel in the wireless
controller's EEPROM.  It looks like when the 'regpair' value is 0x21
then it expects to find ETSI rules for the 2.4 GHz band, allowing use of
channel 13, but it might not.

Does the interface work on channel 13 after installation?  (And assuming
that you install crda.)

[...]

Right, I didn't see any extra clues there.

Ben.

[...]

Yes it does.