Can't connect Raspberry Pi 3B+ Rev. 1.3 to Wifi 5G

[basti <mailinglist@unix-solution.de>]

Hello,

i have a Raspi 3B+ and try to connect to WIFI 5G.

The Access Point is OpenWRT and operate in
AC mode, Channel 64 (5320 MHz).

On the pi side:

root@debian:~# cat /proc/device-tree/model ; echo " ";
Raspberry Pi 3 Model B Plus Rev 1.3
root@debian:~# iwlist wlan0 scanning| grep Freq
                    Frequency:2.412 GHz (Channel 1)
                    Frequency:2.437 GHz (Channel 6)
                    Frequency:2.437 GHz (Channel 6)
                    Frequency:2.462 GHz (Channel 11)
                    Frequency:2.462 GHz (Channel 11)
                    Frequency:2.462 GHz (Channel 11)

root@debian:~# iw reg get
global
country DE: DFS-ETSI
	(2400 - 2483 @ 40), (N/A, 20), (N/A)
	(5150 - 5250 @ 80), (N/A, 23), (N/A), NO-OUTDOOR, AUTO-BW
	(5250 - 5350 @ 80), (N/A, 20), (0 ms), NO-OUTDOOR, DFS, AUTO-BW
	(5470 - 5725 @ 160), (N/A, 26), (0 ms), DFS
	(5725 - 5875 @ 80), (N/A, 13), (N/A)
	(5945 - 6425 @ 160), (N/A, 23), (N/A), NO-OUTDOOR
	(57000 - 66000 @ 2160), (N/A, 40), (N/A)

phy#0
country 99: DFS-UNSET
	(2402 - 2482 @ 40), (6, 20), (N/A)
	(2474 - 2494 @ 20), (6, 20), (N/A)
	(5140 - 5360 @ 160), (6, 20), (N/A)
	(5460 - 5860 @ 160), (6, 20), (N/A)

There is no Wifi 5G found.
I have no idea what is wrong there.