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I'm trying to build a Pi-powered wireless webcam, but I'm running into a problem where, after the Pi has been running for a while, it somehow breaks the wireless network. When this happens, both the Pi as well as any other devices connected to the network become unavailable, and new devices are not able to connect to the network anymore. This only affects the 2.4 GHz network on my dual-band router; the 5 GHz network is unaffected, as are wired devices. A router restart fixes the problem most of the time, but sometimes I also have to unplug the WiFi adapter and then plug it back in.

The setup is as follows:

  • Raspberry Pi: Model B and Pi 2 (problem occurs with both)
  • Power supply: 2.1 A
  • WiFi adapter: this one (Ralink 5370 chipset, connected directly to the Pi, power saving is off)
  • Camera: official NoIR camera (activity LED is off)
  • Software: motionPie; Raspbian + streamEye (problem occurs with both configurations)

The problem does not seem to occur when the Pi is connected to a wired network, or when nothing is accessing the camera (e.g. just running Raspbian, with a connected ssh session). When connected to WiFi and the camera is in use, however, the problem occurs, sometimes within minutes, sometimes it takes hours.

Neither RPi is overclocked. The WiFi adapter is supposed to be able to run directly from the Pi without a powered hub. The Model B Pi can also run RasPlex using the same WiFi adapter with zero problems. When hooked up to a display and with a user logged in, nothing out of the ordinary shows up on the console.

Any suggestions? I really need to make this work over WiFi.

  • You could look in /var/log/syslog for clues about anything unusual, but this is really an issue with your router and not the pi or adapter -- even if they are misbehaving in some way, a wifi router should not be overwhelmed by this, and an individual device cannot shut down a network (sans serious cracking). It is sort of like believing that your car is the problem because streetlights go off when you drive by. Could the car be a cause? Sure, but there would have to be something very wrong with the streetlights in order for a normal car to be such an effective cause. – goldilocks Sep 14 '15 at 21:15
  • I'll have to install Raspbian, because right now I'm testing with motionPie and it doesn't seem to have /var/log/syslog. Any tips on what to look out for? As for the car and streetlights analogy, I'm not sure it's a very good one, because a car does not interact with streetlights, but a WiFi adapter does with a router. Since the problem doesn't occur with the RPi idling or running Rasplex, for instance, there has to be something about the specific combination of hardware and software that causes this. – Indrek Sep 14 '15 at 21:19
  • I'm sure if you check with a physicist s/he'll come up with some ways a car can interfere with certain kinds of streetlight via electromagnetic fields, just not in a way that is ever likely to happen, which is what I'm saying about devices, adapters, and networks: Again, an individual device cannot disable a network without serious and intentional cracking unless something is wrong with the network equipment beyond the device. Otherwise every clown in town would be out there shutting down wifi networks in office buildings, libraries, fast food restaurants, etc. – goldilocks Sep 14 '15 at 21:29
  • If you want to solve this mystery, you'll need to find out what the possibilities are, and those have nothing specific to do with the pi. I suggest you try our larger, more general sibling site, Super User. – goldilocks Sep 14 '15 at 21:29
  • The wireless network isn't disabled completely, it's still visible to devices, and the router itself keeps working fine. So while you might be right in saying that an individual device cannot accidentally disable a network, I'm sure you'll agree it can disrupt one. Is it possible that something is causing the RPi and its wireless adapter to flood the network with garbage traffic and this is causing the issue? Also, until I actually see another device causing the same symptoms, I'm going to assume that it does have something to do with the Pi. Otherwise I would have asked on SU already. – Indrek Sep 14 '15 at 21:36
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I can't give you the magic answer, but there are certainly some things you can test.

1) If you power down the RPi when the network is "down", does it work for the other hosts again (without restarting the router)? If not, your router is broken. This may not be helpful, but your router absolutely should not fail because of any bad acting on the part of any member of the network.

2) Have you tried with any other wifi dongles?

3) You could try to capture packets on your network and see if anything interesting happens right before the network dies. You can do this using tcpdump on the RPi on the wlan interface, and saving this to a file (use a reasonable snaplen to avoid this file becoming huge) which you can then stop and look at when the network dies.

You can also try to capture all Wifi packets from another host, but this can be tricky - you can review https://wiki.wireshark.org/CaptureSetup/WLAN for examples of how you could do this.

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