Posts Tagged ‘wireless network connection’

RaspberryPi Zero loses connectivity

Friday, July 9th, 2021

I have had a problem with RPI Zero. The system was working fine, and then it did not. I am using Raspbery Linux (Debian-based) with kernel 5.10.17+. Once a while (usually with network load) the system loses connectivity. Everything seems to be fine, if you have a serial/USB console there, but the wireless network fails. This problem was also mentioned here.

My workaround was to create a script with a cron scheduling. I have identified that the fault lies with the wlan driver, and it needs to get reloaded. So cron calls this script every minute, like this:

*/1 * * * * /usr/local/sbin/check_connection.sh

And the script (/usr/local/sbin/check_connection.sh) has this in it:

1
2
3
4
5
6
7
8
9
#!/bin/bash
# DST is the network gateway
DST=192.168.230.1
if ! ping -c 5 -t 5 $DST > /dev/null
then
  #/usr/sbin/reboot
  /usr/bin/logger "Restarting wlan0 network driver"
  /usr/sbin/rmmod brcmfmac && /usr/sbin/modprobe brcmfmac roamoff=1
fi

Set this script to be executable, and your RPI Zero should work just fine. This is not a solution, but a workaround, of course, but it works well.

I’ve been away for a week due to work abroad

Sunday, April 2nd, 2006

And had the chance to be in one of the largest server farms I’ve ever been to. Could not take pictures, though.

We were connected to a proxied and limited network, inside the organization, with a limited set of allowed web sites. It was terrible. Then I’ve figured that if I purchase wireless network connection (which was available), I can use my laptop as a router, running NAT on this connection, while still being physically connected to the internal network. Security hole? Sure is, but not mine 🙂

So I’ve connected that way using PCMCIA wireless card (for some reason my internal Orinoco_PCI card refused to talk to that wireless network. I should try to find time to diagnose this issue). So I’ve had a configuration as follows:

1) wlan0 (PCMCIA wifi via ndiswrapper) – Internet

2) eth2 (First wired network card) connected to the internal LAN, and used as GW for one of my team

3) eth1 (Orinoco_PCI wifi card) in ad-hoc mode, acting as GW for another one of my team, who sat just far enough so I could not throw him a cable.

It worked, and worked fine.

Regarding other issues, I’ve noticed that my laptop was at its top, but felt it was hardly enough. For example – I used SkyPE. When in a voice call, my CPU went up to a stable 80-85% utilization. It is high. It means that if I do anything else, I get choppy sound (which I did get). It was good we’ve had such a long unused time at the customer’s place. Lots of waiting you can pass while in a voice call, and for free.

Well, it was educative. I’ve learned some additional things of how things work on a very large-scale environments, with the cons and pros of it. Was fun.