Super User is a question and answer site for computer enthusiasts and power users. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

How can I see what's causing my 3G dongle to disconnect from the Internet?

I'm using a Huawei K3565 USB 3G dongle on my Raspberry Pi.

Using wvdial and sakis3g I can connect to my current provider (GiffGaff) - but only for a few seconds.

For example, I can ping 3 - 4 times, or download approx 25,537 bytes.

Then the modem disconnects.

I don't think this is a power issue - I'm using a 1.2A charger with no keyboard or screen attached. I also have sufficient credit :-)

So, any idea what is causing it to disconnect? Which logs can I look at?

share|improve this question
What makes you think it's not a power issue? – Jivings Jul 5 '12 at 12:34
Well, that's a good point. Raspberry Pi recommends 700mA for powering the device. Most 3G dongles need no more than 500mA. 500+700=1200. But I'll try with a 1.8A charger to see if that makes a difference. – Terence Eden Jul 5 '12 at 15:29
Yes, well that's 700mA for powering the Pi alone. You're trying to power things with it as well. – Jivings Jul 5 '12 at 20:03
Interestingly, with a 1.8A charger, it connect for about 3 times as long before suddenly disconnecting. Are there any specific logs I can look at? – Terence Eden Jul 6 '12 at 10:14
Not for this. Look at @AlexChamberlain's answer. The usb port doesn't provide enough power for your dongle. – Jivings Jul 6 '12 at 10:27
up vote 2 down vote accepted

The current on the RPi outputs is limited to 140mA; try it through a powered hub.

share|improve this answer
That did the trick. Thanks! – Terence Eden Jul 13 '12 at 6:58

I found a tutorial in "Cooking Hacks" explaining how to use 3G with the Raspi through GPIO:

They have launched a shield that allows our Raspi to be connected to a server or to make calls through a 3G Module.

share|improve this answer
If it is possible to include the important part of the external post in your answer, please do so (since the link you provided may not work tomorrow!) – Dave Oct 16 '12 at 9:18

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .