Ever left your headphones connected when putting your laptop to sleep and then got greeted with the "Dummy Output" problem and didn't feel like rebooting your laptop just to get audio working again? Me too, many times.
So instead of restarting the whole laptop, I finally realized that restarting the audio service alone is enough to fix the issue, here is the command to do it:
systemctl --user restart pulseaudio.service
Assuming it is a temporary problem and audio was working fine up until now, this command should be enough to get it working again.
If it never worked in the first place, that might be a driver issue, in which case this command won't help much. If that is the case, I could suggest trying to install a newer kernel to see if your Wi-Fi card got support on more recent releases of it.