Re: Can't seem to use 5GHz APs with Intel wireless

## Dhananjay Balan (mail_at_dbalan.in):

> On Sat, Jun 02, 2018 at 12:37:12AM +0200, Christoph Moench-Tegeder wrote:
> > Did you try adding "mode 11a" to select 5GHz band? (This might be
> > out-of-date, as my WiFi stuff is all on 11) (currently I'm also
> > using 2.4GHz only, for compatibility with some devices and the fact
> > that I have quite some trouble running 2.4GHz and 5GHz from the same
> > interface at the same time).
> 
> I did a bit more testing, I have to admit that I am not well versed in
> wifi internals.

Here's the non-technical overview: https://en.wikipedia.org/wiki/IEEE_802.11
(The real details can be really gory, but this should be good enough).

> 1. ifconfig wlan0 list aps shows my aps having rate 54M (Im not entirely
>    sure what this means).
>    But however when I connect to it, it shows up as 11g

A data rate of 54 MBit/s would be perfectly in sync with 11g - 20MHz
channel width, OFDM modulation, 2.4 GHz. And we see that in this line:

>         ssid LA03 channel 6 (2437 MHz 11g ht/20) bssid 52:d9:e7:47:c0:c2

And this shows that even MIMO ("Multiple Input, Multiple Output" has
been activated (that's the "n" in "11ng"):

>         media: IEEE 802.11 Wireless Ethernet MCS mode 11ng

The 5GHz part of 802.11 is 802.11a (and related, like ac), there's no
5GHz band in 11g.

I'm a little puzzled about this:
>         regdomain FCC4 country DE authmode WPA2/802.11i privacy ON

Is the regdomain/country setting correct for your area and matches your
AP? Especially in the 5GHz band there are some "gaps" - not all channels
may be used in all countries (because of possible interference with
radar equipment and other stuff). See:
https://en.wikipedia.org/wiki/List_of_WLAN_channels#5_GHz_(802.11a/h/j/n/ac/ax)

Regards,
Christoph

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