scarecrowsong
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Pi 4 4GB- Wifi not working when resolution is set too high

Fri Oct 18, 2019 4:29 am

Hello folks, I have the strangest issue with my Pi4 4Gb model. If the resolution is set to 1920x1080 or 1024x768 the wifi sees the APs but will not connect. No error message just type in the password and it never connects. If however, I set my resolution to 800x600 everything works as normal. Why would the resolution have anything to do with the wifi issue??? Also for reference I am using the official PSU and have nothing extra plugged into the Pi4. HALP!

EnricoF
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Re: Pi 4 4GB- Wifi not working when resolution is set too high

Fri Oct 18, 2019 7:32 am

Hi to all,
Luckily I found this post, I was becoming crazy.
I have the same problem can not connect to the wifi.
So I made same test at different resolution.
I connected to the access point at a lower resolution and then try to load fast.com at different screen resolutions.
Here the results (yes = works):

1920x1080 yes
1600x1200 no
1680x1050 yes
1280x1024 no if switching from 1600, yes if 1440 or 1680
1440x900 yes
1280x960 yes
1280x800 yes

Very wired behavior
Some idea?

Enrico

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HawaiianPi
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Re: Pi 4 4GB- Wifi not working when resolution is set too high

Fri Oct 18, 2019 8:02 am

Odd problem.

First thing that comes to mind is a poorly shielded HDMI cable (or adapter)?
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EnricoF
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Re: Pi 4 4GB- Wifi not working when resolution is set too high

Fri Oct 18, 2019 8:23 am

The HDMI cable is the official one supplied by the online shop.
An external usb wifi dongle works perfectly to any resolution.
I discover the problem after updating my pi today. ( apt-get dist-upgrade) Not sure was there before.
The pi is the 4GB one.

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HawaiianPi
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Re: Pi 4 4GB- Wifi not working when resolution is set too high

Fri Oct 18, 2019 8:51 am

Are you using any USB 3.0 devices?

USB 3.0 is known to interfere with 2.4GHz wireless?
My mind is like a browser. 27 tabs are open, 9 aren't responding,
lots of pop-ups...and where is that annoying music coming from?

EnricoF
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Joined: Sat Dec 10, 2016 12:13 pm

Re: Pi 4 4GB- Wifi not working when resolution is set too high

Fri Oct 18, 2019 9:12 am

Thanks for yours replay.

Test made with only keyboard and mouse into usb2 ports.

The external usb wifi dongle, connected to usb3, that always work have an external antenna and it's very close to the pi too.

The wpa_supplicant error shown in wpa_cli is wrong authentication error.

Don't you have the same problem? Have you tested?

timg236
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Re: Pi 4 4GB- Wifi not working when resolution is set too high

Fri Oct 18, 2019 9:21 am

Please can you check for any mmc or SDIO errors in dmesg in the failing case ?

It might be worth adding these lines in config.txt to rule out clock configuration to SDIO issues before thinking about RF interference

core_freq=500
core_freq_min=500

EnricoF
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Re: Pi 4 4GB- Wifi not working when resolution is set too high

Fri Oct 18, 2019 9:59 am

Can not find any error, nor one related to mmc or SDIO in dmesg.

Adding the two line:
core_freq=500
core_freq_min=500
in config.txt doesn't fix the problem

In my config.txt I have the line:
hdmi_force_hotplug=1
hdmi_ignore_edid=0xa5000080
config_hdmi_boost=4
hdmi_group=2
disable_overscan=1

because I'm using a tv Asanzo model 32T660N and it was the only way to get HDMI video out.
Just to say a Chromcast ultra works perfectly.

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HawaiianPi
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Re: Pi 4 4GB- Wifi not working when resolution is set too high

Fri Oct 18, 2019 4:36 pm

EnricoF wrote:
Fri Oct 18, 2019 9:12 am
Don't you have the same problem? Have you tested?
WiFi on my two Pi4s is not as good as some other computers I own, but it's not the worst either, and I have no trouble connecting to my router (located down the hall in another room). My wpa_supplicant.conf has both 2.4 and 5GHz networks, and it usually connects to the faster 5GHz.
My mind is like a browser. 27 tabs are open, 9 aren't responding,
lots of pop-ups...and where is that annoying music coming from?

amgrays
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Re: Pi 4 4GB- Wifi not working when resolution is set too high

Sun Nov 10, 2019 9:09 pm

I have had similar problems:
- in one location, removing the USB card reader from USB3 to USB2 socket appeared to resolve the issue (I managed to destroy a 32G card while plugged into the USB3 port for some reason but that is another issue - or maybe related)
- in another location I have managed to pretty much proved that having a monitor plugged into HDMI0 causes WiFi to fail (haven't tried changing resolution but have it set in config.txt as follows:

Code: Select all

hdmi_force_hotplug=1
hdmi_force_mode=1
hdmi_group=2
hdmi_mode=42
Steps to reproduce are:
  • Boot with monitor off
  • Ensure WiFi connected OK and ping google.com - responses shown
  • Turn on monitor - responses stop
I then plugged the monitor into HDMI1 and the problem disappears.

BTW I have an official Raspberry Pi power supply but I can't help feeling that this is a power-related hardware issue rather than software config.

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mahjongg
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Re: Pi 4 4GB- Wifi not working when resolution is set too high

Sun Nov 10, 2019 9:23 pm

Sounds like HDMI signals interfering with Wifi signals to me.

amgrays
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Re: Pi 4 4GB- Wifi not working when resolution is set too high

Mon Nov 11, 2019 2:25 am

Some test results on HDMI0, hdmi-safe=1 (640x480 60Hz). Monitor connection is with 10cm micro HDMI to female HDMI connected to standard HDMI M-M (approx 2m)

1) Monitor unplugged: Av = 56ms

Code: Select all

--- google.com ping statistics ---
87 packets transmitted, 85 received, 2.29885% packet loss, time 255ms
rtt min/avg/max/mdev = 41.953/55.984/180.752/29.012 ms
2) Monitor plugged in to HDMI0: Av = 585ms

Code: Select all

--- google.com ping statistics ---
86 packets transmitted, 83 received, 3.48837% packet loss, time 443ms
rtt min/avg/max/mdev = 39.836/584.915/1448.568/478.726 ms
3) Monitor plugged in to HDMI1: Av = 123ms

Code: Select all

--- google.com ping statistics ---
94 packets transmitted, 84 received, 10.6383% packet loss, time 635ms
rtt min/avg/max/mdev = 41.775/123.215/555.718/98.295 ms
So, even though WiFi is still operational, WiFi performance is significantly degraded with monitor connected to HDMI0. There is less degradation when the monitor is connected to HDMI1. Interference between HDMI and WiFi seems like a plausible scenario. In the meantime suggestions are:
  • Use HDMI1 output connector
  • Use the lowest resolution possible
  • Don't use WiFi
  • Wait for the next hardware iteration that will hopefully fix the issue :)

jamesh
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Re: Pi 4 4GB- Wifi not working when resolution is set too high

Mon Nov 11, 2019 10:19 am

amgrays wrote:
Mon Nov 11, 2019 2:25 am
Some test results on HDMI0, hdmi-safe=1 (640x480 60Hz). Monitor connection is with 10cm micro HDMI to female HDMI connected to standard HDMI M-M (approx 2m)
Do you have a cable that does NOT need the adapter, preferably 1M? I wonder if the adapter cable and/or the extra plugs, are leaking RF.
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amgrays
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Re: Pi 4 4GB- Wifi not working when resolution is set too high

Mon Nov 11, 2019 10:54 pm

jamesh wrote:
Mon Nov 11, 2019 10:19 am
Do you have a cable that does NOT need the adapter, preferably 1M? I wonder if the adapter cable and/or the extra plugs, are leaking RF.
No I don't but will get one and report back. Would that explain a significant different between HDMI0 and HDMI1?

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