RPi 4 unable to connect to WiFi [solved]

[guestxyz]

Used the official Raspi4 power supply. Should be enough: after unplugging it delivers power for about 15s.... and Raspi won't boot up during that time. Very nasty in view of missing reset button.

The WiFi problem looks like a bug. If I start with low resolution, the 2.4GHz network works nicely. If I go to 1920x1080 wlan0 either shows "not available" or so, or it shortly shows a neighboring network labeled with a red "5G", depending on what I click at the top of the screen, but my 2.4GHz network is not recognized. With my router set to 5GHz (+2.4) it works.

So, if there were a power problem, it must be within the Pi4B board (Copper traces too thin?).

[pica200]

That's strange. The only cause i can think of is noise from HDMI but the ports are far away from the WiFi + BT chip/antenna, the later is shielded and HDMI is probably not quite in the same frequency range. Maybe a RPi engineer has an explanation for this? I could not observe this behavior at all with full resolution.

[jaguay]

Hello everyone,

I just had the same problem when I disconnected manually from my wifi network and did not wanted to connect again.

Tried everything you guys wrote in this post, without success.

The solution was to change my SSID Name and password.

Sometimes the simplest solutions are the harder to find, because are so obvious

Cheers

Jorge

[mahjongg]

That's strange. The only cause i can think of is noise from HDMI but the ports are far away from the WiFi + BT chip/antenna, the later is shielded and HDMI is probably not quite in the same frequency range. Maybe a RPi engineer has an explanation for this? I could not observe this behavior at all with full resolution.

It could depend on how well the HDMI cable is shielded, the wires carry digital signals, which are square waves, meaning they have harmonic contents that go way beyond the frequency of the HDMI signals. If the HDMI shielding is weak or absent, the wires act like antennae, and could radiate a wide spectrum of frequencies.
in practice HDMI signals are already filtered, (using https://en.wikipedia.org/wiki/Low-volta ... _signaling) but the same principle applies, and good shielding is still essential.

[assadollahi]

I can confirm that changing screens will allow the WiFi to connect.
Pi4, 4GB, latest Buster (26 Sept 2019), powered via USB-C battery bank, 3A
Side note: Same battery bank has 3A USB output as well as 3A USB-C output,
the pi4 only works in a stable manner when connected via USB-C to USB-C.
Strange, hm? Back to screen vs Wifi:

1) small screen 1: 1920x1200, big screen 2: 2560x1440, Wifi doesn't connect
2) remove screen 2, reboot: Wifi connects!
3) re-connect screen 2, but set resolution also to 1920x1200, reboot: Wifi works!
4) removed small screen 1 and put screen 2 in 1920x1200 resolution: Wifi works!
5) puttin screen 2 into 2560x1440: Wifi doesn't work anymore!

Could it be that higher resolutions have higher demand in power and thus Wifi is underpowered?
However: When powering from battery via USB-C, at no time I get the lightning bolt. So it shouldn't
be a power issue?

[bjtheone]

Sounds suspiciously like an radiated interference issue. I would try buying an good, very well shielded HDMI cable for the higher res monitor and see if that changes the behaviour. Given there is not a flood of complaints about issues with high res monitors, I highly doubt the issue is in the shielding and traces on the PCB (thought you could have a defective one).

Another interesting test would be to see what happens if you only have monitor 2 connected, running at the higher resolution. If that still has issues, I would definitely try a better cable.

[Shadow_7]

I've had issues where turning on an LCD display near the TV or LED lights would interfere with ATSC signal reception (OTA TV). On an older HDTV (circa 2006). You might fool around with some tin foil to shield things. Assuming the wifi is not near the TV/Display. I originally got my mom to switch to linux for a bit because windows wifi would forget it had a wifi device if the signal dropped below 34% strength. A tin foil covered pizza box on the opposite side of the desktop helped improve the signal strength (but didn't improve windows). A couple zip lock bags, electrical tape and wrapping odd coax joiner/splitter/extension points with tin foil too for the TV. But country life some 40+ miles from the big cities. You might also change your wifi channel. Older cordless phones would interfere with channel 11, and all your neighbors probably went with the factory default channel 1. So try channel 6. Just a thought. Newer LED lights seem to interfere less with things, but are still more problematic to wireless things than incandescent bulbs were. Try turning off the lights and see if wifi works again. A strange world we live in these days.

[netikras]

I doubt it's HDMI cable.

I had some doubts at first hence bought other 2 RPI4s believing the prior one(s) to be defective. So here's what happened.

At work I have a need to monitor multiple charts at once LIVE. So we bought a 4K display and a rpi4 to drive the dashboard. Popped in a copy of the latest Raspbian Buster and fired it all up.

At first all was nice and dandy, 2 or 3 days later the magic started to happen.

Out of the blue network all the configuration disappeared and I no longer could bring the network up (P.S. I was using WIFI connection and a BT keyboard). Every time I tried to connect to any WIFI AP I got the same weird IP address that did not conform to either of the networks. Routing table was empty, adding routes manually did not bring the network up. Tried multiple restarts as well. In the end decided to reflash the image and start all over again. That's the first thing that was weird and not sure whether in any way relevant to your topic, but.. maybe?

The new image was also working perfectly for a few days. After that something new started to happen - at some mornings when I came in to the office I used to find the RPi4 disconnected from WIFI. Reconnecting back to the network did work most of the times - the other times I had to restart the device (sudo shutdown -r now). That happened a few times. Still connected to the same 4K display.

Later on something new started happening: the BT keyboard could no longer connect to the RPi. Multiple attempts to rfkill the bluetooth device did not help (or maybe did, just not enough?) - the keyboard still was not able to connect, although sometimes I could see the cursor move a few milimeters (the keyboard has a trackpoint). Restarting the RPi "fixed" the bluetooth thing every time.

We got another RPi hoping that one was defective. The new one had the same issues too. I brought the old one home hoping to do some tests and identify whether it is OS or HW issue. I hooked up the serial connectors and connected to RPi with my laptop. No display connected (I do not have HDMI displays). I set up WIFI connection to my router and connected via ssh for more convenient access. After a while I walked away to have lunch and came back to find a frozen ssh connection. Hooked up UART adapter again to find that WIFI got disconnected, wlan0 got the same weird IP address and an empty routing table. Could not reconnect to my wifi router without a restart. Let me repeat myself: NO display was connected to the RPi. Before restart I saw some errors (bcm? Something I translated into Broadcom at that moment) with an error code -5<something> (-52? -53? Can't remember). Restarted the device and the network came back up. Could not reproduce that error ever since. But I saw it at the RPi in the office a few days later (w/ 4K display), when BT failed again.

[not in chronological order] another weird issue was happening with all the RPis and that was the reason why I bought the 2nd RPI4. As I was setting up the first RPI4 I did not yet have the 4k display, so I was using my 1920x1080 monitor. All the set-up process went fine, then we got the 4k display. Plugging the rpi4 to the display was troublesome - it could not stretch out the image to 4k. Reflashed the sd card and rebuilt the dashboard on the 4k display this time. All went peachy. Then plugged in my monitor (can't remember the reason why tho) and all I could see was black. Not even the RPI logo was seen when booting up. Nothing. Only black. But the OS booted up as I saw new records in syslog later on. Tried messing with boot parameters in boot.conf (?) - didn't help. Since then even 4k randomly does not work. Reflashing the sd card again did fix it. Apparently RPi4 (or Raspbian Buster?) does not like to be switched between different resolutions, if either of those resolutions is 4k. If I set RPI4 up using 4k only - it works well and is stable (image-wise). If I try to connect it to any other display - video stops working randomly on any displays you are to connect the RPi to from that moment on, until you reinstall the OS. But that was the point when I ruled my first RPi defective. That was a wrong move as other 2 RPI4s I got (all from different vendors) had all the same issues



Not sure whether my story has any value in this context. Maybe it could suggest it's not the HDMI cable to blame network issues. Maybe it has something to do with internals of the board as I got network outage even w/o any video cables connected. Maybeit has something to do with on-board graphics, as they are obviously misbehaving. And maybe it's just an OS issue since after reinstalling the OS things get back to normal. What's still bothering me is that I still have the first RPI4 at home connected and booted up waiting for network to go down again to have a proper post-mortem analysis. Could not make it happen - it's been a few weeks now.

[pica200]

Maybe this should be moved to a new thread. This sounds to me like the driver for the WiFi and Bluetooth combi is going nuts or the firmware of it. Edge case with non-standard conform router?

[jamesh]

I think this is the same as this

https://www.raspberrypi.org/forums/view ... 0&start=25

There's a test firmware out - sudo rpi-update will get it - can you see if it helps?

[mohit1]

Having same problem

What i observed is once wifi connects
then doing 2 reboots
It wont auto connect to wifi

Also you need to powercycle 2-5 times to get it connected to wifi once

[DevoRP]

My WIFI will work at 800x600 but it will not work at 1024x768 or 1920x1200.

[moostr]

Holly molly -- after 2 days of trying everything, changing the screen resolution from 2560x1440 to 1920x1080 finally worked!

I'm on Pi4B, single monitor, 5.5-3A power, USB mouse, BT keyboard, all up-to-date, otherwise all default settings. The wifi works when I boot into CLI (console). In desktop mode, it connects to the router, obtains an IP address, but does not connect to the internet (no ping), then disconnects from router after some minutes.

I'll try to narrow down the cause later or maybe try 5GHz. Sigh of relief !!

[moostr]

Little more info. Ping times at 2560x1440:

Code: Select all

pi@raspberrypi:~ $ ping -I wlan0 8.8.8.8
PING 8.8.8.8 (8.8.8.8) from 192.168.0.111 wlan0: 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=53 time=283 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=53 time=325 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=53 time=23.2 ms
64 bytes from 8.8.8.8: icmp_seq=4 ttl=53 time=8.42 ms
64 bytes from 8.8.8.8: icmp_seq=5 ttl=53 time=178 ms
64 bytes from 8.8.8.8: icmp_seq=6 ttl=53 time=163 ms
64 bytes from 8.8.8.8: icmp_seq=7 ttl=53 time=208 ms
64 bytes from 8.8.8.8: icmp_seq=8 ttl=53 time=159 ms

and at 1920x1080:

Code: Select all

pi@raspberrypi:~ $ ping -I wlan0 8.8.8.8
PING 8.8.8.8 (8.8.8.8) from 192.168.0.111 wlan0: 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=53 time=3.81 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=53 time=6.10 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=53 time=3.30 ms
64 bytes from 8.8.8.8: icmp_seq=4 ttl=53 time=3.30 ms
64 bytes from 8.8.8.8: icmp_seq=5 ttl=53 time=3.45 ms
64 bytes from 8.8.8.8: icmp_seq=6 ttl=53 time=3.63 ms

iwconfig reports roughly same SNR between -30 and -40 dBm in both cases.

Finally, another telling tale:

Code: Select all

[Monitor connected (2560x1440)]
64 bytes from 8.8.8.8: icmp_seq=59 ttl=53 time=5371 ms
64 bytes from 8.8.8.8: icmp_seq=60 ttl=53 time=4331 ms
64 bytes from 8.8.8.8: icmp_seq=62 ttl=53 time=2254 ms
64 bytes from 8.8.8.8: icmp_seq=63 ttl=53 time=1215 ms
64 bytes from 8.8.8.8: icmp_seq=64 ttl=53 time=178 ms
[Disconnect monitor]
64 bytes from 8.8.8.8: icmp_seq=65 ttl=53 time=4.13 ms
64 bytes from 8.8.8.8: icmp_seq=66 ttl=53 time=4.82 ms
64 bytes from 8.8.8.8: icmp_seq=67 ttl=53 time=6.13 ms
64 bytes from 8.8.8.8: icmp_seq=69 ttl=53 time=5.29 ms

Connect to 5 GHz wifi is back to normal at 2560x1440.

[pica200]

If the range allows it definitely use 5 GHz. It's far better than the oversaturated 2.4 GHz band at the cost of some range.

And yeah, this is known and mostly caused by badly shielded HDMI cables.

[omegawea]

I have just got my rpi4 and tested it this weekend. Its wifi module gave me a headache...

A brand new rpi4 requires rpi-update to get the wifi at least working. Then I ran into issue with occasionally drop off, maybe due to resolution and HDMI0.
https://www.raspberrypi.org/forums/view ... p?t=254640
So I changed to HDMI1 (no audio) and resolution to 720x400. The wifi could be working for a longer while until I tried to watch youtube.

I am thinking of using an external wifi module as alternative, ideally connect if internal wifi failed, any clue how to set it up?

[omegawea]

I have just got my rpi4 and tested it this weekend. Its wifi module gave me a headache...

A brand new rpi4 requires rpi-update to get the wifi at least working. Then I ran into issue with occasionally drop off, maybe due to resolution and HDMI0.
https://www.raspberrypi.org/forums/view ... p?t=254640
So I changed to HDMI1 (no audio) and resolution to 720x400. The wifi could be working for a longer while until I tried to watch youtube.

I am thinking of using an external wifi module as alternative, ideally connect if internal wifi failed, any clue how to set it up?

I finally get it working by either disabling the conky widget or increase the router wifi channel to 13.

I read it somewhere was an offical suggestion to set the router channel > 10. Hope this help some of you.

[sidhi]

I'm having the same problem.... When I change the resolution from 1920 x 1080 to 1280 x 720, the wifi suddenly disconnected and unable to connect....

I tried :

Code: Select all

sudo apt-get update
sudo apt-get upgrade -y
sudo apt-get dist-upgrade -y
sudo apt-get install rpi-update -y
sudo rpi-update
sudo apt-get purge rpi-update -y

sudo apt autoremove -y

and even I tried

Code: Select all

sudo systemctl enable networking

But when I tried to return the resolution to 1920 x 1080 it works...

but when I change it to 1280 x 720 back to wifi disconnected... Any idea to fix it ?
.

[davidcoton]

Have you tried the suggestions in this thread?

[kreegan99]

I had the same problem. I set my resolution to 1920x1080 and my wifi stopped working. I ran the rpi-update as the engineer above suggested, rebooted and then things started working again. I haven't done very much testing here though.

There was a lot of talk earlier on in the thread about noise and HDMI cables. I wanted to add the data point that I run my pi4 headless, and still had the problem. So not likely cable related at all.

[ParametricPi]

Had the same problem with Raspi 4B.
Problem was dependent on screen resolution (!!).
With 1920x1080, wlan0 became disconnected after it was ok at lower screen resolutions. Was in 2.4GHz band.
After turning on 5GHz in the router and going into the network preferences (right click the network icon top right on screen) and SSID ... and checking "automatically configure options" the connection remains stable (so far ).

The method explained here (network icon, select SSID, check "automatically configure options") worked for me, instantly. My RPI4/4GB is now connected over 5G wifi. Many thanks.

I am running a qHD/60Hz monitor by the way, no issues whatsoever. I also have a heatsink case and have overclocked the CPU to 2.175 GHz, on the old RPI microUSB powersupply with a microUSB to USB-C adapter. I actually find it/mine a stoical little PC for daily use with few issues. The wifi issue is actually the only issue I have encountered. And it turns out it's user failure, it was just a setting I didn't know about.

[doveoscar]

Similar issues here with a new Pi 4. Now I've got it booting, it can see a 5g wifi network but won't authenticate, but it is happy connecting to non-5g. Monitor is 1920*1080 and I'm using the outermost HDMI connector.

Re. booting, it wouldn't even get past the rainbow on boot, using the more central HDMI connector; but when I connected to the other connector, suddenly all was good. There are clearly issues between the wifi chip and the display outputs radiating at each other, and it seems we all have our particular work rounds. Can't have been tested very well.

[HawaiianPi]

Monitor is 1920*1080 and I'm using the outermost HDMI connector ... it wouldn't even get past the rainbow on boot, using the more central HDMI connector

On the Pi4 with a single monitor, the default port is HDMI-0, the one closest to the USB-C power input. HDMI-1 is for a secondary display, and has some limitations compared to HDMI-0. As you have found, the GPU test shows on either screen, but the GUI loads on HDMI-0 when booting with a single screen. There may be a way to force HDMI-1 using new port specific options in config.txt, but it's just simpler to use HDMI-0.

Note:
In the Desktop/GUI screen configuration utility, HDMI-0 is called HDMI-1 (and HDMI-1 = 2) due to some upstream issues that are beyond the control of RPF. So don't get confused by that (use the numbers on the board silkscreen).

pi4hdmi.jpg (63.93 KiB) Viewed 17322 times

Sorry I can't help with your WiFi issues. I haven't run into that myself. Both of my Pi4 computers connect to my 5GHz WiFi fine. Only thing I can say is that "5G" refers to mobile networks, and 5GHz is dual band WiFi (along with 2.4GHz), which I assume is what you meant. When trying to troubleshoot it's best to use accurate terminology, to avoid confusion.

Does your router use the same SSID for both frequencies? I have heard of issues in the past when that is the case (don't know if that's still a problem). In my experience, the Pi4's WiFi is not the greatest, but it's not the worst either. If you are having trouble authenticating to a weak WiFi network, that may be contributing.

[LordMontag]

Same thing happened to me (complete newbie - had my pi for 1 week). After a reboot could not get normal wifi to connect.

Aftwr reading below suggestioni changed to routers 5g band point and all was good. I would not have thought it was related to display settings, but i had uses the advanced display settings menu before i rebooted. My memory is a bit hazy, but i thought i had escaped witbout changing anything... but would have picked no32: 1080p 24Hz. This is also manually set in my config file.

[pclavier]

I can confirm TOO that changing screens will/may affect your WiFi connectivity.
Pi4B, 4GB, Retropie Buster 4.6 for Pi4 , powered via USB-C power supply 4.2A

First time I used it WiFi worked perfectly, I then changed my screen resolutions to this:

hdmi_group=2
hdmi_mode=16

Next thing I know WiFi not working, could tell why and drove me crazy for a while. Just read this and thought of moving my resolution back to its initial state. And voila! I have WiFi working again.

Anyways, not sure what the relations is here...

I can confirm that changing screens will allow the WiFi to connect.
Pi4, 4GB, latest Buster (26 Sept 2019), powered via USB-C battery bank, 3A
Side note: Same battery bank has 3A USB output as well as 3A USB-C output,
the pi4 only works in a stable manner when connected via USB-C to USB-C.
Strange, hm? Back to screen vs Wifi:

1) small screen 1: 1920x1200, big screen 2: 2560x1440, Wifi doesn't connect
2) remove screen 2, reboot: Wifi connects!
3) re-connect screen 2, but set resolution also to 1920x1200, reboot: Wifi works!
4) removed small screen 1 and put screen 2 in 1920x1200 resolution: Wifi works!
5) puttin screen 2 into 2560x1440: Wifi doesn't work anymore!

Could it be that higher resolutions have higher demand in power and thus Wifi is underpowered?
However: When powering from battery via USB-C, at no time I get the lightning bolt. So it shouldn't
be a power issue?