my wlan works right after i installed ubuntu 11.04, after several hours it just stop detecting my wlan. my wlan is an Intel PRO/Wireless 3945ABG [Golan} Network Connection (rev 02). i downloaded driver for linux from intel website but i don't know how to install it. PLEASE HELP!
I have the same network hardware in my laptop. It works just fine with the standard driver that came with Ubuntu. When it stops seeing wireless networks, that usually means I've accidentally toggled the wifi kill switch on the front of my laptop.
I've had occasional problems, through, with earlier versions of Ubuntu. Sometimes those problems were resolved by unloading and reloading the driver module:
sudo modprobe -r iwl3945 sudo modprobe iwl3945
although I should mention that at one point the unload command used to cause the entire system to freeze. Caveat emptor.
I realise the OP to this question was last seen in July, so my answer is more generic. To resolve problems like this will probably need some interaction to try out stuff.
- Suggestion 1:
Why do you need to install a new driver? Sometimes the version in the kernel is buggy. Fortunately, the kernel team do release a backport of new & updated drivers & their firmware a few months after each Ubuntu release. For natty, you can install this by:
sudo apt-get install linux-backports-modules-cw-2.6.39-generic
- Suggestion 2:
Check if the wireless card is actually blocked. Running
rfkill list is very useful - if the wireless is actually recognised there can be two types of blocking being reported - a soft block and a hard block.
A hard-block is likely to be a hardware switch - a physical hardware switch/ a Fn key switch or maybe a BIOS option.
A soft-block can sometimes be resolved by running:
sudo rfkill unblock wifi; sudo rfkill unblock all
Followed by either:
to start the wireless lan OR select "enable wireless" on Network Manager.
- Suggestion 3:
Removing and readding the kernel module can sometimes activate the wireless card. It is also very useful to diagnose what the Kernel errors are:
sudo modprobe -r iwl3945 sudo modprobe iwl3945 dmesg | tail -n 50
Have a close look at the output - sometimes a firmware update can resolve this - see the linked question below.
- Suggestion 4:
modprobe options above should write out a
iwl3945.conf file in
dmesg message could indicate that an alernative value(s) are required e.g.
alias wlan0 iwl3945 options iwl3945 disable_hw_scan=1
Using Lubuntu 18.04 on a machine with an Intel PRO/Wireless 3945ABG, it turned out that it was the power saving that was killing the device and not returning it correctly. In the boot it warned that trying to suspend the device may lead to corruption - which peaked my interest.
According to another AskUbuntu post  by @user3273814, you simply need to disable the power management for your wireless device:
To turn off power management, go to
/etc/NetworkManager/conf.d/default-wifi-powersave-on.confand you will see
wifi.powersave = 3
It's now been running as a wireless server for 2 days without issue, so I assume this is now fixed given it would only go for a few hours before. How annoying!
Please see that post for more details.