nixos-hardware/apple/macbook-pro/12-1/README.md

MacBook Pro 12,1

Wireless won't get reconnected after resume/hibernate

The wifi driver is unloaded before suspend/hibernate to workaround driver issues. This means it might be required to restart your wifi deamon i.e. wpa_supplicant:

powerManagement.powerUpCommands = ''
  ${pkgs.systemd}/bin/systemctl restart wpa_supplicant.service
'';
};

You can apply this to your network management software of choice.