Why wireless connection stop to work?

Question

today I correctly installed the driver for the TP-LINK TL-WN725N USB wireless adapter, then I setted up the wifi using the wpa-supplicant as explained in this tutorial:

http://www.maketecheasier.com/setup-wifi-on-raspberry-pi/

This worked fine untill this evening. Then suddenly it stopped to work when I try to connect in SSH and the Raspberry is on the wireless (or rather it should be, as this is not in the list of my router's DHCP connected Client)

The strange thing is that the USB wirless adapter blink so I think that this is not a driver problem.

If I try to connect it by the ethernet I have no problem. It appear in my router's DHCP connected Client and I can connect to it by SSH.

When I connect to it using ethernet if I perform an ifconfig command I obtain:

pi@raspberrypi ~ $ ifconfig
eth0      Link encap:Ethernet  HWaddr b8:27:eb:2a:9f:b0  
          inet addr:192.168.1.9  Bcast:192.168.1.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:48 errors:0 dropped:0 overruns:0 frame:0
          TX packets:59 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:6006 (5.8 KiB)  TX bytes:8268 (8.0 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:8 errors:0 dropped:0 overruns:0 frame:0
          TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:1104 (1.0 KiB)  TX bytes:1104 (1.0 KiB)

wlan0     Link encap:Ethernet  HWaddr e8:94:f6:19:80:4c  
          UP BROADCAST 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)

So it seems that the wlan0 USB wireless adapter driver is correctly loaded.

If I remove the USB wireless adapter and put it again into the USB port, the lasts lines of dmesg log is:

[   20.303172] smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup
[   20.306340] RTL871X: set bssid:00:00:00:00:00:00
[   20.306726] RTL871X: set ssid [g\xffffffc6isQ\xffffffffJ\xffffffec)\xffffffcd\xffffffba\xffffffba\xffffffab\xfffffff2\xfffffffb\xffffffe3F|\xffffffc2T\xfffffff8\x1b\xffffffe8\xffffffe7\xffffff8dvZ.c3\xffffff9f\xffffffc9\xffffff9a\xffffff9aD\xffffffa7\x1a\xffffffa0\x1a\xffffff8b] fw_state=0x00000008
[   21.614585] RTL871X: indicate disassoc
[   21.908495] smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0x45E1
[   25.006282] Adding 102396k swap on /var/swap.  Priority:-1 extents:1 across:102396k SSFS
[   26.247997] RTL871X: nolinked power save enter

As you can see some of these line are related to the RTL871X that is my USB wireless adapter, but I don't know is that these line report an error or if it is all ok.

Looking at the adapter status I obtain:

pi@raspberrypi ~ $ ip  link list dev wlan0
3: wlan0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN mode DORMANT qlen 1000
    link/ether e8:94:f6:19:80:4c brd ff:ff:ff:ff:ff:ff

As you can see the mode is DORMANT but I think that this is normal because now I am connected using ethernet.

I tryied to set up the adapter but it seems that I obtain no result, infact:

pi@raspberrypi ~ $ sudo ip link set dev wlan0 up 
pi@raspberrypi ~ $ ip  link list dev wlan0
3: wlan0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN mode DORMANT qlen 1000
    link/ether e8:94:f6:19:80:4c brd ff:ff:ff:ff:ff:ff
pi@raspberrypi ~ $ sudo ip link set dev wlan0 up 

This is my /etc/network/interfaces file content and it is ok:

auto lo

iface lo inet loopback
iface eth0 inet dhcp

allow-hotplug wlan0
iface wlan0 inet manual
wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf
iface default inet dhcp

and it is the /etc/wpa_supplicant/wpa_supplicant.conf that I think is ok (I did not change it compared to when it worked):

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
network={
        ssid="MY-NETWORK"
        psk="mypassword"
        key_mgmt=WPA-PSK
}

and infact if I execute a network scan I correctly find MY-NETWORK in the network list,infact:

pi@raspberrypi ~ $ sudo iwlist wlan0 scan | grep ESSID
                    ESSID:"TeleTu_74888B0060AD"
                    ESSID:"MY-NETWORK"
                    ESSID:"FASTWEB-1-PT6NtjL4TOSe"
                    ESSID:"DC"

So I reboot the system and I remove the ethernet cable but when I try to connect again to my raspberry I obatin the following error message:

andrea@andrea-virtual-machine:~$ sudo ssh  [email protected]
ssh: connect to host 192.168.1.9 port 22: No route to host

It seems that it can't connect using wireless.

What could be the problem? What am I missing? How can I solve this situation?

Tnx

Answer 1

Try to set wireless-power off in your /etc/network/interfaces after the wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf line.

Something like:

iface wlan0 inet manual
wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf
wireless-power off