Built-in WiFi doesn't see 5Ggz environment

#1

Hi,
Probably the question is more about the armbian, but I’ll ask her.
Ihave two Rock-pi with armbian 228 legacy with absolut identical setup (regional etc. ) one pi has no built-in
WiFi, It uses realtek usb dongle 81xx don’t remember with ac
suppport. If i type nmcli dev wifi realtek
Shows аll access points in 5ggz enviroments. But second rockpi with built-in wifi Sees only 2.4ggz 1-13 channels. Dmesg cfg80211 Shows that 5xxxxxxxxxKhz freq. is turned on.
What could be the reason?
thanks in advance

#2

Hmm, if i look in the technical specifications of the realtek chip, i can´t find support for the 5.0 GHz network.

#3

Thank you, but why dmesg Shows 5ggz freq on this chip🙃

#4

The 80211 is not your wifi chip. The chip is a relatek RTL8723DS-CG.

#5

I am understand cfg80211 is configuration API for Linux.
But why dmesg Produces “Fake News” like this:

cfg80211: (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp), (dfs_cac_time)
[Sat Dec 5 20:38:12 2020] cfg80211: (2400000 KHz - 2483500 KHz @ 40000 KHz), (N/A, 2000 mBm), (N/A)
[Sat Dec 5 20:38:12 2020] cfg80211: (5150000 KHz - 5250000 KHz @ 80000 KHz, 200000 KHz AUTO), (N/A, 2000 mBm), (N/A)
[Sat Dec 5 20:38:12 2020] cfg80211: (5250000 KHz - 5350000 KHz @ 80000 KHz, 200000 KHz AUTO), (N/A, 2000 mBm), (0 s)
[Sat Dec 5 20:38:12 2020] cfg80211: (5470000 KHz - 5725000 KHz @ 160000 KHz), (N/A, 2698 mBm), (0 s)
[Sat Dec 5 20:38:12 2020] cfg80211: (5725000 KHz - 5875000 KHz @ 80000 KHz), (N/A, 1397 mBm), (N/A)
[Sat Dec 5 20:38:12 2020] cfg80211: (57000000 KHz - 66000000 KHz @ 2160000 KHz), (N/A, 4000 mBm), (N/A)
I have never seen 5ghz lines on my pure 2.4ghz dongles😒

#6

Interesting, what command did you use?

#7

This is output from dmesg -T. I don’t know why does he write this🤔

Hello from Hessen too

#8

These are not the frequencies supported by the chip, but the regulatory rules for frequency/power combinations for a particular country.
https://wireless.wiki.kernel.org/en/developers/regulatory/processing_rules

#9

Thanks, теперь понятно:face_with_raised_eyebrow: