Raspberry Pi kicks itself off of networks when joining a new network

Question

$ uname -a
Linux Adam-Pi 3.18.5+ #744 PREEMPT Fri Jan 30 18:19:07 GMT 2015 armv6l GNU/Linux

I've discovered an interesting problem with my networking setup with my RasPi. I have it connected to three different networks:

• A wireless network with Internet access using a USB dongle and wpa-supplicant
• A wired Ethernet connection to my private network (no Internet access)
• An OpenVPN client daemon connected to a cloud server

The problem happens whenever I connect to a new interface. When I connect my USB dongle, for example, the Raspberry Pi will kick itself off of the wired connection. The same thing happened when I recently configured it with my new VPN - it would disconnect itself from the wireless network. When I looked into it today, I found this on dmesg after connecting to my VPN:

[13134.532384] wlan0: deauthenticating from xx:xx:xx:xx:xx:xx by local choice (Reason: 3=DEAUTH_LEAVING)
[13134.596079] cfg80211: Calling CRDA to update world regulatory domain

It looks as if it was configured to disconnect under a certain condition.

After looking into the first problem I had encountered with ethernet and wlan, it appears as if the Pi completely reboots when the dongle is plugged in. I can't access the reason why (because the Ethernet connection is killed as soon as the WiFi dongle is plugged in). This problem has truly stumped me, I hope someone out there has the experience to solve this.

Answer 1

After looking into the first problem I had encountered with ethernet and wlan, it appears as if the Pi completely reboots when the dongle is plugged in.

That's not unusual; I have a wifi adapter that causes this. The problem is that the A/B pis can't provide enough power to properly fulfill the USB 2.0 standard. It's still enough to run a small adapter, but when first plugged in, the sudden current draw causes a small voltage drop which browns the pi out momentarily.

This may not necessarily always be enough to reset the whole thing, in which case it might just cause a sudden ethernet disconnect. I haven't found that a better power supply makes any difference, but then I haven't experimented too much -- it is not a big deal to me.

Not quite as perplexing as the Pi 2's light sensitivity.