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So I've been trying to trouble-shoot this myself for weeks.

I have a Pi3 (and a Pi4, though the 4 causes no issues).

My Pi3 is fully up to date, on Raspbian Linux 4.19.81-v7+ This issue persisted prior to updates too.

The Pi serves the following tasks:

  • Runs a cron job for a twitter bot
  • Runs a push notification server for Apple PNS
  • Runs PiHole (also acts as my DHCP and DNS server in my home)
  • Executes a DynamicDNS job to update my domain registrar with my public IP
  • SSH/VPN endpoint as I have a port forwarded to this device from my router

The load on the device is like 0.01 0.02 0.01 most of the time

Normally this all works perfectly for 3-6 days or so, then at some random point in time, I notice my MacBook or PC will stop working and it's clearly because the Pi is not serving DNS requests. I then notice that renewing a DNS lease does nothing, so the Pi has stopped serving these functions.

Also the Pi is not pingable and will not respond to SSH requests.

So I've been trawling through the logs and the unusual thing (to me) is that there are still items being printed during the "downtime", I have included the logs here below in a pastebin if anyone would like to view them.

https://pastebin.com/brV3k0nJ

Because my twitter bot runs every 10 mins, I know that this log above captures the 'falling over' about between 1am and 2am or so.

I did consider a hardware issue but I don't think it is one. It's really weird, can anyone help?

Nov 20 01:12:19 raspberrypi dhcpcd[466]: wlan0: carrier lost
Nov 20 01:12:19 raspberrypi dhcpcd[466]: wlan0: deleting address fe80::6bb:e56d:3d5a:8974
Nov 20 01:12:19 raspberrypi avahi-daemon[385]: Withdrawing address record for fe80::6bb:e56d:3d5a:8974 on wlan0.
Nov 20 01:12:19 raspberrypi avahi-daemon[385]: Leaving mDNS multicast group on interface wlan0.IPv6 with address fe80::6bb:e56d:3d5a:8974.
Nov 20 01:12:19 raspberrypi avahi-daemon[385]: Interface wlan0.IPv6 no longer relevant for mDNS.
Nov 20 01:12:19 raspberrypi avahi-daemon[385]: Withdrawing address record for 192.168.0.248 on wlan0.
Nov 20 01:12:19 raspberrypi avahi-daemon[385]: Leaving mDNS multicast group on interface wlan0.IPv4 with address 192.168.0.248.
Nov 20 01:12:19 raspberrypi avahi-daemon[385]: Interface wlan0.IPv4 no longer relevant for mDNS.
Nov 20 01:12:19 raspberrypi dhcpcd[466]: wlan0: deleting route to 192.168.0.0/24
Nov 20 01:12:19 raspberrypi dhcpcd[466]: wlan0: deleting default route via 192.168.0.1
Nov 20 01:12:19 raspberrypi wicd[383]: sending commands to master dhcpcd process
Nov 20 01:12:19 raspberrypi dhcpcd[31919]: sending commands to master dhcpcd process
Nov 20 01:12:19 raspberrypi dhcpcd[466]: control command: /sbin/dhcpcd -k wlan0
Nov 20 01:12:19 raspberrypi dhcpcd[466]: wlan0: removing interface
Nov 20 01:12:20 raspberrypi kernel: [344915.570800] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
Nov 20 01:12:20 raspberrypi kernel: [344915.570988] brcmfmac: power management disabled
Nov 20 01:12:20 raspberrypi wicd[383]: sending commands to master dhcpcd process
Nov 20 01:12:20 raspberrypi dhcpcd[31941]: sending commands to master dhcpcd process
Nov 20 01:12:20 raspberrypi dhcpcd[466]: control command: /sbin/dhcpcd -k docker0
Nov 20 01:12:20 raspberrypi dhcpcd[466]: docker0: removing interface
Nov 20 01:12:20 raspberrypi avahi-daemon[385]: Withdrawing address record for 172.17.0.1 on docker0.
Nov 20 01:12:20 raspberrypi avahi-daemon[385]: Leaving mDNS multicast group on interface docker0.IPv4 with address 172.17.0.1.
Nov 20 01:12:20 raspberrypi avahi-daemon[385]: Interface docker0.IPv4 no longer relevant for mDNS.
Nov 20 01:12:20 raspberrypi kernel: [344915.833591] IPv6: ADDRCONF(NETDEV_UP): docker0: link is not ready
Nov 20 01:12:20 raspberrypi wicd[383]: Failed to connect to non-global ctrl_ifname: docker0  error: No such file or directory
Nov 20 01:12:24 raspberrypi kernel: [344919.963658] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
Nov 20 01:12:24 raspberrypi kernel: [344919.963694] brcmfmac: power management disabled
  • What Raspbian version do you use? Do you use Raspbian Buster? What exactly is the problem? All five tasks stopped working randomly? All together or at different times? What network interfaces do you use? Do you use docker? If so, for what? – Ingo Nov 20 '19 at 19:50
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There is NO Raspbian Linux 4.19.81-v7+
You probably have Raspbian GNU/Linux 10 (buster) running kernel 4.19.81-v7+

You have probably broken your system by running rpi-update

"In normal circumstances there is NEVER a need to run rpi-update as it always gets you to the leading edge firmware and kernel and because that may be a testing version it could leave your RPi unbootable". https://www.raspberrypi.org/forums/viewtopic.php?p=916911#p916911 Even the rpi-update documentation now warns "Even on Raspbian you should only use this with a good reason. This gets you the latest bleeding edge kernel/firmware."

sudo apt-get update; sudo apt-get install --reinstall raspberrypi-bootloader raspberrypi-kernel will put it back to the latest supported kernel/bootcode.

  • 1
    Thanks for that, I had this issue prior to upgrading the kernel. In fact I only upgraded to the beta kernel because I was having this issue. Downgrading didn’t solve it. – Woodstock Nov 21 '19 at 7:47
  • @Woodstock I have asked some questions on a comment to your question. Do you like to get support and may answer them? – Ingo Nov 21 '19 at 11:11
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In the end this issue was caused by my Virgin Media "SuperHub 3.0" router with it's dynamic wifi channel switching.

I disabled it about 11 days ago and not a blip of an issue since.

This also explains why it occurred more often when I was using my laptop upstairs in my house, something which I thought was just my imagination, but obviously an action that forced the router to switch channels.

I don't know if there is a solution on the Pi side, it's just running the standard network stack, so I'm surprised this occurred.

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