Wifi works but is not seen?

[Smoot187]

I have done a search and am almost sure this has not been asked before, especially since it is sort of an obscure problem, but one I have had with both of my Pi's so far. Model B, standard Raspbian install.

I can connect an ethernet cable, browse the web (on the pi), VNC, ssh, etc.

I have connected the wifi dongle (standard TP-link one that comes in a bundle) and scan, connect to my wireless network ok.

I can turn the pi off, restart it and it will automatically connect to the wireless network (after auto logging in and booting to the desktop) which is great.. IF I wanted to use the pi as a working machine, but I would like it to be headless, or at least independant enough that I can move it away from my office (downstairs, outside etc)

the problem is that when connected via wifi, I cannot ssh in, or ping, VNC or anything. It is like it does not exist, my IP scanner does not even pick it up - therefore making it pretty useless

Is this something that someone has came across before?

(I also had the exact same problem with a previous Pi running xbmc - I thought it could be my router, but there is nothing random in the config that would warrant this behaviour)

Many thanks!

[pjc123]

OK. Two things to check.

1) First make sure that you have the following lines in your /etc/network/interfaces file for whatever wireless interface you are using (wlan0, wlan1, etc.). Then reboot to try it out.


auto wlan0
allow-hotplug wlan0
wireless-power off



2) Otherwise, I have a post which may be the same problem.

http://www.raspberrypi.org/phpBB3/viewt ... 5&p=316193

Now I wasn't able to find the cause, but I was able to fix the symptom. I run a script that checks every 15 seconds that an ip has been issued, and if not, resets the wireless interface. I have got it to the point that my headless pi boots with an ip 100% of the time now. I never tried to run it just once at boot because I don't know if it would catch a "no ip" condition in just one shot, but certainly you could extend the check to every minute or so, if a longer wait is acceptable. I just left it that way because of so many posts indicating that their connection was lost randomly.

I found a script to do this, but it did not work for a couple of reasons, which I fixed:
1) I needed to add the full path to the ifconfig, ifdown and ifup commands.
2) The ifconfig method that was used just did not work, so I changed it to a ping check.

Here is that thread:

http://www.raspberrypi.org/phpBB3/viewt ... 26&t=16054

Now, my TP-Link is probably a different model than yours because I doubt they would pack it in a bundle, but maybe it has the same chipset and that may be the common denominator. What model do you have?