== I'm unable to connect my USB HDD | External HDD is failing to mount automatically ==

exfat is not supported in NixOS by default - since there are legality issues still with exFAT filesystem.

<syntaxhighlight lang="bash">su nano /etc/nixos/configuration.nix</syntaxhighlight>

Add this line to your configuration file.
<syntaxhighlight lang="bash">boot.extraModulePackages = [ config.boot.kernelPackages.exfat-nofuse ];</syntaxhighlight>

After saving the file rebuild NixOS:

<syntaxhighlight lang="bash">nixos-rebuild switch"</syntaxhighlight

Restart NixOS