What happened

  • I have faced this issue multiple times after installing debian
  • Each time during installation WiFi worked but after that it didn’t, initially I thought that there was some issue of firmware
  • But this time after installation wifi worked, but nmcli device had a problem, it always showed that the device was unmanaged
  • So I tried different things and finally was able to resolve the issue

Solution (Source)

  • Just add the following line to your grub config (/etc/grub.d/10_linux)
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi=force"
  • After that generate grub config
grub-mkconfig
  • Now just reboot