Same issue here with a Raspberry pi 4 model B Rev 1.1 using the on-board Wifi. I am using this Raspberry as a WiFi access point. This issue happens one or two times after a day of normal use. Usually when here is a lot of traffic in the network (copying files, or reproducing video with the Chromecast). After this happens, all wifi-clients are disconnected and you have to power-off and power-on the Raspberry to get it working again.
You can find all the relevant information attached in this tarball:
https://github.com/raspberrypi/linux/files/4790487/wifi-halted-report.tar.gz
Inside the tarball you can find: daemon.log, dpkg.log, hostapd.conf, ifconfig.log, kernel.log, lsb_release.log, lspci.log and syslog.log
Most relevant logs are located into kernel.log file, lines between 3538 and 3547. There is a time issue into this log file 20:56:37 --> 22:52:47 --> ... --> 22:17:05, not sure if it's related with the issue or not, but is strange that just in that moment of time happens the issue.
Here you can see the error:
3538 Jun 16 20:56:37 raspberrypi kernel: [13183.398916] usb 1-1.1.5.5: USB disconnect, device number 8
3539 Jun 16 22:52:47 raspberrypi kernel: [20153.194747] brcmfmac: brcmf_sdio_hostmail: mailbox indicates firmware halted
3540 Jun 16 22:53:30 raspberrypi kernel: [20196.728384] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout
3541 Jun 16 22:53:30 raspberrypi kernel: [20196.728829] brcmfmac: brcmf_sdio_checkdied: firmware trap in dongle
3542 Jun 16 22:53:33 raspberrypi kernel: [20199.288384] brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout
3543 Jun 16 22:53:33 raspberrypi kernel: [20199.288757] brcmfmac: brcmf_sdio_checkdied: firmware trap in dongle
3544 Jun 16 22:53:33 raspberrypi kernel: [20199.288775] brcmfmac: brcmf_cfg80211_get_station: GET STA INFO failed, -110
3545 ^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@ ^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@ ^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@ ^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@ ^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@ ^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@Jun 16 22:17:05 raspberrypi kernel: [ 0.000000] Booting Linux on physical CPU 0x0
3546 Jun 16 22:17:05 raspberrypi kernel: [ 0.000000] Linux version 4.19.118-v7l+ (dom@buildbot) (gcc version 4.9.3 (crosstool-NG crosstool-ng-1.22.0-88-g8460611)) #1311 SMP Mon Apr 27 14:26:42 BST 2020
3547 Jun 16 22:17:05 raspberrypi kernel: [ 0.000000] CPU: ARMv7 Processor [410fd083] revision 3 (ARMv7), cr=30c5383d
3548 Jun 16 22:17:05 raspberrypi kernel: [ 0.000000] CPU: div instructions available: patching division code
3549 Jun 16 22:17:05 raspberrypi kernel: [ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, PIPT instruction cache
3550 Jun 16 22:17:05 raspberrypi kernel: [ 0.000000] OF: fdt: Machine model: Raspberry Pi 4 Model B Rev 1.1
3551 Jun 16 22:17:05 raspberrypi kernel: [ 0.000000] Memory policy: Data cache writealloc
3552 Jun 16 22:17:05 raspberrypi kernel: [ 0.000000] cma: Reserved 256 MiB at 0x000000001ec00000
Basically I have a bridge br0 between wlan0 and eth0. DHCP server is running on my home router connected to eth0. I am using hostapd to convert wlan0 into an Access Point. If you need more detailed information, I can provide it.
Hope this helps!
-d
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