hakenhand
Posts: 6
Joined: Wed Jul 31, 2019 9:37 am

Raspberry Pi 4b WiFi 5Ghz (ac) bugs

Wed Jul 31, 2019 11:43 am

DE Wifi Country.jpeg
DE Wifi Country.jpeg (105.92 KiB) Viewed 803 times
US Wifi Country.jpeg
US Wifi Country.jpeg (117.19 KiB) Viewed 803 times

Hello, everybody.
I come from Germany.
I have problems with the WIFI of the Raspberry 4b.
The RPi 4b does not connect to the same channel width (80mhz) as the RPi 3b+.
The RPi 4b only connects according to the wifi n standard, not according to the ac standard, therefore with lower bandwidth.

I have attached two screenshots to make it clear.

If I set the Wifi Land to US the connection to the Fritzbox is at ac standard and 80mhz channel width but the connection is constantly broken and the signal strength is very low.

I use software with the latest updates on both Raspberry Pi. Both devices are about 3 meters away from the router.

How can I change this behavior of the RPi 4b?
Greetings


PS. translated with Deepl.com

hakenhand
Posts: 6
Joined: Wed Jul 31, 2019 9:37 am

Re: Raspberry Pi 4b WiFi 5Ghz (ac) bugs

Wed Aug 07, 2019 8:00 am

Hello
does anyone have a similar problem or even a solution?

Thank you

hakenhand
Posts: 6
Joined: Wed Jul 31, 2019 9:37 am

Re: Raspberry Pi 4b WiFi 5Ghz (ac) bugs

Thu Nov 07, 2019 11:59 pm

just wanted to say that despite all the updates in Raspbian till today, nothing has changed yet.
Still slow Wifi,
still the same situation as in my first post.

Any help is welcome.
Thank you

trejan
Posts: 935
Joined: Tue Jul 02, 2019 2:28 pm

Re: Raspberry Pi 4b WiFi 5Ghz (ac) bugs

Fri Nov 08, 2019 12:27 am

The 3B+ and 4B use the same Cypress CYW43455 chip for WiFi/Bluetooth. Have you updated to the latest version of Raspbian on both Pi boards?

Diablo2_Fan
Posts: 14
Joined: Thu Aug 01, 2019 6:47 pm

Re: Raspberry Pi 4b WiFi 5Ghz (ac) bugs

Fri Nov 08, 2019 4:13 pm

I have similar problems after the EEPROM update to 000137ab.
A 2.4 GHz connection to the AP isn't possible anymore and the 5 GHz connection is really weak :-(

Michael Kofler from pi-buch reported wifi problems, too:
https://pi-buch.info/eeprom-updates-fue ... erry-pi-4/

hakenhand
Posts: 6
Joined: Wed Jul 31, 2019 9:37 am

Re: Raspberry Pi 4b WiFi 5Ghz (ac) bugs

Sat Nov 09, 2019 11:16 am

now that i actually equipped the 3b+ with the last raspbian buster, the 3b+ shows the same error as the Pi4

what could be the reason?
thank you
Image

renice123
Posts: 102
Joined: Tue Oct 15, 2019 3:56 pm

Re: Raspberry Pi 4b WiFi 5Ghz (ac) bugs

Sat Nov 09, 2019 11:31 am

Based on your messages, the conclusion is obvious - the cause of errors is to use the Baster OS. I also already found some errors critical for me. Mounting cloud storage is still not working well. Buster is an unstable system. We will suffer =)

Diablo2_Fan
Posts: 14
Joined: Thu Aug 01, 2019 6:47 pm

Re: Raspberry Pi 4b WiFi 5Ghz (ac) bugs

Mon Nov 11, 2019 9:38 am

Changing the HDMI resolution solved my WIfi problem.
Also plugging the cable to the micro-HDMI-1 port improved the signal quality.

I think it's a HDMI bug, because I'm using the official HDMI-cable.

jamesh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
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Re: Raspberry Pi 4b WiFi 5Ghz (ac) bugs

Mon Nov 11, 2019 10:06 am

Diablo2_Fan wrote:
Mon Nov 11, 2019 9:38 am
Changing the HDMI resolution sloved my WIfi problem.
Also plugging the cable to the micro-HDMI-1 port improved the signal quality.

I think it's a HDMI bug, because I'm using the official HDMI-cable.
Thanks for the datapoint -that's quite interesting.

I wonder if you could try some tests? Are you able to SSH in, if so can you turn off the HDMI when running in the problematic mode, then see if the Wifi improves?

Use `vcgencmd display_power 0` to turn off power to the current display. (https://www.raspberrypi.org/documentati ... cgencmd.md)

You can check wifi SNR using, IIRC, `iwlist accesspoints`, so that would also be useful information to have when running various different HDMI resolutions.
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PhilE
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 2490
Joined: Mon Sep 29, 2014 1:07 pm
Location: Cambridge

Re: Raspberry Pi 4b WiFi 5Ghz (ac) bugs

Mon Nov 11, 2019 11:50 am

"iwlist accesspoints" doesn't work for me. You can get most information from "iwconfig wlan0", just not the channel width. "iw wlan0 info" gets you a different subset including channel width but not the SNR. "iw reg get" will show what is supported for each group of channels, but that might not include a handshake with the WiFi firmware to verify that it is possible and permitted.

What's that GUI you are using? It doesn't look like a standard Raspbian component, and it would help to stick to standard, command line utilities when debugging this.

hakenhand
Posts: 6
Joined: Wed Jul 31, 2019 9:37 am

Re: Raspberry Pi 4b WiFi 5Ghz (ac) bugs

Mon Nov 11, 2019 12:52 pm

if the question which gui I use is addressed to me, it is the default Raspbian Buster desktop.
The screenshots above are from the web interface of my Wifi-router.

PhilE
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 2490
Joined: Mon Sep 29, 2014 1:07 pm
Location: Cambridge

Re: Raspberry Pi 4b WiFi 5Ghz (ac) bugs

Mon Nov 11, 2019 1:07 pm

I too am only getting 40MHz channels except when selecting the US regulatory domain, but for me there's no difference in behaviour between 3B+ and 4B.

Starting with HDMI connected, run this set of commands. Leave it running for 5-10 seconds, then unplug the HDMI cable and hit Return on the keyboard to mark the changeover point, leave that for 5-10 seconds then reconnect the cable, hitting Return again. I don't see any significant difference between the connected and disconnected case, but if anything the link is worse without HDMI connected - where I set and how I lean over the Pi has a much larger effect, so watch your posture.

Where possible it helps to see measurements from the Pi's perspective, although seeing SNR/Link Quality from both sides is interesting. If you see that the Pi's Link Quality varies less than the Router's then it might be that the monitor is interfering with Router.

Kendek
Posts: 128
Joined: Thu Jul 25, 2019 4:39 pm
Location: Kaposvár, Hungary

Re: Raspberry Pi 4b WiFi 5Ghz (ac) bugs

Mon Nov 11, 2019 1:29 pm

PhilE wrote:
Mon Nov 11, 2019 1:07 pm
I too am only getting 40MHz channels except when selecting the US regulatory domain, but for me there's no difference in behaviour between 3B+ and 4B.
Qualcomm error message when trying to connect to AC-only mode:

Code: Select all

deny assoc request, no vht caps in pure 802.11ac mode
If doing pure 802.11ac mode, don't accept STAs without VHT capabilities.

It is good if country=US.

Diablo2_Fan
Posts: 14
Joined: Thu Aug 01, 2019 6:47 pm

Re: Raspberry Pi 4b WiFi 5Ghz (ac) bugs

Mon Nov 11, 2019 8:07 pm

jamesh wrote:
Mon Nov 11, 2019 10:06 am
I wonder if you could try some tests? Are you able to SSH in, if so can you turn off the HDMI when running in the problematic mode, then see if the Wifi improves?

Use `vcgencmd display_power 0` to turn off power to the current display. (https://www.raspberrypi.org/documentati ... cgencmd.md)

You can check wifi SNR using, IIRC, `iwlist accesspoints`, so that would also be useful information to have when running various different HDMI resolutions.
I haven't SSH but I wrote this quick & dirty script:

Code: Select all

#!/bin/bash

echo "values with enabled hdmi:"
echo
iwconfig wlan0
sleep 1
echo
echo
echo "values with disabled hdmi:"
echo
vcgencmd display_power 0
sleep 30
iwconfig wlan0
sleep 1
vcgencmd display_power 1
read -n 1 -s
Here are two examples:

1920x1080:
I think it's interesting because it's not able to connect to the AP while the screen is on.
values with enabled hdmi:

wlan0 IEEE 802.11 ESSID:off/any
Mode:Managed Access Point: Not-Associated Tx-Power=31 dBm
Retry short limit:7 RTS thr:off Fragment thr:off
Power Management:on



values with disabled hdmi:

display_power=0
wlan0 IEEE 802.11 ESSID:"myssid"
Mode:Managed Frequency:5.18 GHz Access Point: mymac
Bit Rate=121.5 Mb/s Tx-Power=31 dBm
Retry short limit:7 RTS thr:off Fragment thr:off
Power Management:on
Link Quality=46/70 Signal level=-64 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0

display_power=1


1280x1024:
quality and level are very different here:
values with enabled hdmi:

wlan0 IEEE 802.11 ESSID:"myssid"
Mode:Managed Frequency:5.18 GHz Access Point: mymac
Bit Rate=108 Mb/s Tx-Power=31 dBm
Retry short limit:7 RTS thr:off Fragment thr:off
Power Management:on
Link Quality=38/70 Signal level=-72 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0



values with disabled hdmi:

display_power=0
wlan0 IEEE 802.11 ESSID:"myssid"
Mode:Managed Frequency:5.18 GHz Access Point: mymac
Bit Rate=108 Mb/s Tx-Power=31 dBm
Retry short limit:7 RTS thr:off Fragment thr:off
Power Management:on
Link Quality=47/70 Signal level=-63 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0

display_power=1

EDIT: Update
2.4 GHz is affected the same way.

I downgraded the EEPROM to 00013701 and the 2.4 GHz and 5 GHz Wifi seems to be more stable.

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