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I'm working on an African education project that uses the rpi. I got an issue which is critical so hopefully someone out there can help. Thanks in advance! When I connect a usb modem to the pi all works well until I access the wlan0 network when it crashes/hangs. The wlan0 network is critical for use in the field, its how coaches access the rpi but they need to send us info with the usb modem. Here some CSI observations (you will see I'm only a quarter geek sorry!):

  1. If usb modem is in but not connected to net it does not cause a problem
  2. When the pi starts up it says my ip address is 1.1.1.1 192.168.1.1 (1.1.1.1. is wlan0 and 192.x is the usb modem)
  3. No issues with wlan0 if the dongles is not in
  4. The problem is only triggered if I go onto wlan0, all is well up to that point
  5. Below the ifconfig before I go onto the wlan0 (is man.wlan0 ok?)
  6. Further below my /etc/network/interfaces file

pi@raspberrypi ~ $ ifconfig

eth0      Link encap:Ethernet  HWaddr b8:27:eb:2c:6d:a3  
          inet addr:10.1.1.5  Bcast:10.1.1.255  Mask:255.255.255.0  
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1  
          RX packets:192 errors:0 dropped:0 overruns:0 frame:0  
          TX packets:63 errors:0 dropped:0 overruns:0 carrier:0  
          collisions:0 txqueuelen:1000  
          RX bytes:27986 (27.3 KiB)  TX bytes:11605 (11.3 KiB)  

eth1      Link encap:Ethernet  HWaddr 58:2c:80:13:92:63  
          inet addr:192.168.1.100  Bcast:192.168.1.255  Mask:255.255.255.0  
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1  
          RX packets:78 errors:0 dropped:0 overruns:0 frame:0  
          TX packets:76 errors:0 dropped:0 overruns:0 carrier:0  
          collisions:0 txqueuelen:1000  
          RX bytes:9765 (9.5 KiB)  TX bytes:7724 (7.5 KiB)  

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0  
          UP LOOPBACK RUNNING  MTU:65536  Metric:1  
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0  
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0  
          collisions:0 txqueuelen:0  
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)  

mon.wlan0 Link encap:UNSPEC  HWaddr 00-C1-40-50-0B-7C-00-00-00-00-00-00-00-00-00-00  
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1  
          RX packets:141 errors:0 dropped:0 overruns:0 frame:0  
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0  
          collisions:0 txqueuelen:1000  
          RX bytes:46288 (45.2 KiB)  TX bytes:0 (0.0 B)  

wlan0     Link encap:Ethernet  HWaddr 00:c1:40:50:0b:7c  
          inet addr:1.1.1.1  Bcast:1.1.1.255  Mask:255.255.255.0  
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1  
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0  
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0  
          collisions:0 txqueuelen:1000  
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B) 

more /etc/network/interfaces

auto lo  

iface lo inet loopback  
iface eth0 inet dhcp  

auto wlan0  
iface wlan0 inet static  
  address 1.1.1.1  
  netmask 255.255.255.0  
  pre-up sudo iptables -t nat -A PREROUTING -i wlan0 -p tcp -j DNAT --to-destination 1.1.1.1  
  pre-up sudo python /opt/ka-lite-pi-scripts/redirect_port80_to_port8008.py &  

allow-hotplug eth1  
  • You should probably clarify some stuff here: 1) What do you mean by "crashes/hangs"? It bumps into something and then dangles there, or is there actually something real and specific you are observing? 2) What do you mean by "go onto wlan0"? You stand on top of it? What specificly are you actually doing -- do not use euphemisms. The ifconfig output you posted shows both wlan0 and the usb modem eth interfaces as up and connected. Finally, what model pi is this? If it isn't an A+/B+, how are these devices powered? – goldilocks Jan 13 '15 at 21:37
  • Hi, sorry for delayed response - new to the site and did not see it. Answers to questions: – edulution.org Jan 14 '15 at 8:10
  • Looks like my answers did not save above. Since then I have isolated the problem more. If I connect to the wlan0 network with a laptop the problem arises, through a tablet no issues. Weird I know. Answers to questions 1) logging onto wlan0 (with laptop) seems to kill all the networks and I can't access the pi, even through wireless usb keyboard 2) I mean log on to wlan0 network 3) The ifconfig shown is just before logging onto wlan0 with laptop 4) Model B+ with 2.1A battery. – edulution.org Jan 14 '15 at 17:40
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USB power is limited on a Pi so the USB modem and WiFi might draw too much current.

  1. Try a higher current PSU for the Pi
  2. Then try a powered USB hub

Seting up WiFi Usb dongle

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