If you're using TLP http://linrunner.de/en/tlp/tlp.html then you can disable power management when on battery by changing the option "WIFI_PWR_ON_BAT=5" to "WIFI_PWR_ON_BAT=1" about halfway down in the file "/etc/default/tlp".
If you're using TLP http:// linrunner. de/en/tlp/ tlp.html then you can disable power management when on battery by changing the option "WIFI_PWR_ON_BAT=5" to "WIFI_PWR_ON_BAT=1" about halfway down in the file "/etc/default/tlp".