2020-09-29

Linux WiFi disabled after a long period of no activities: bad wifi powersave

I have Lubuntu 18.04 on my Dell Inspiron 5000 laptop. A recurring problem is that the WiFi becomes unavailable after I leave my laptop on for a long period. The problem won't appear if I always put it back to sleep before leaving it idle for a long time. Once the problem happens, I have to turn off and turn on the computer exactly twice to fix it. Rebooting (e.g., sudo reboot) won't even fix it. 

Today I was so annoyed by this problem so I googled around. I am not alone. Nearly everyone who had the issue points to WiFi power management. Some say that it just took a really long time, e.g., 30 seconds, for the WiFi adapter to wake up from sleep. Some has the problem after system wake up from suspension -- but I don't have this problem. 

 It turns out that the most effective fix is to simply disable WiFi power management to prevent the WiFi adapter from going into powersave mode. Just edit

/etc/NetworkManager/conf.d/default-wifi-powersave-on.conf
and change the line
wifi.powersave = 3
into
wifi.powersave = 2

However, this also means that you will waste energy on WiFi when the computer is idle. 

Below are some links for those who want more information. 

  • https://www.reddit.com/r/Lubuntu/comments/54endb/help_new_install_but_wifi_disconnects_randomly/ 
  • https://core.docs.ubuntu.com/en/stacks/network/network-manager/docs/reference/snap-configuration/wifi-powersave

  • https://askubuntu.com/questions/1022203/how-to-prevent-wifi-sleep-after-suspend 
  • https://askubuntu.com/questions/695867/disable-wifi-power-management/961460
  • https://askubuntu.com/questions/1030653/wifi-randomly-disconnected-on-ubuntu-18-04-lts

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