Try using the following commands to turn off power management for your wireless:
Originally Posted by braganfamily
Replace eth0 with the actual name of your interface.
sudo iwconfig eth0 txpower fixed
sudo iwconfig eth0 power off
sudo iwconfig eth0 commit
The third command may give an error as "feature not supported" that can be ignored.
Either one of the first two commands should work and will take effect immediately, _until_ your next reboot.
So give the commands, then surf for an hour or two to check if it is effective. If it is effective, you can add the commands to your "/etc/rc.local" to take effect on every reboot.
Note that in the rc.local file, the last line should not be disturbed (ie, "exit 0")