I have never installed a nix package on Steam Deck under SteamOS before. I followed his instructions from this website , everything is ok without problem, then I installed an app with this command nix-env -iA nixpkgs.mullvad-vpn. When I finish installing an app, I open Mullvad GUI, I see a message

Unable to contact the Mullvad system 
service, your connection might be unsecure. 
Please troubleshoot or send a problem 
report by clicking the "Learn more" button.

I don’t know how to fix this issue

My Nix version is 2.32.4 and my SteamOS version is 3.7.13

  • Corbin@programming.devEnglish
    4·
    28 days ago

    Hi! Welcome to the Nix community. You’ve made an unfortunate choice for your first package, because VPNs usually need to be integrated with system networking to function properly, and Nix without a daemon or NixOS is not able to do that. A distro has multiple pieces, including package management (putting executables and libraries onto your disk) and system configuration (interacting with the low-level hardware). Nix is a package manager; NixOS is Nix and also system configuration and some other stuff like booting.

    For the specific case of Mullavad, I found this community documentation:

    Warning: Mullvad VPN currently only works if systemd-resolved is enabled.

    All you need to know here is that systemd is part of the system configuration; systemd-resolved is part of how some Linux systems look up names. Nix’s version of Mullavad VPN is only compatible with a specific NixOS configuration.

    Honestly, it’s great to hear that the GUI and nix-env are working for you; those are things that often break on unusual targets. It sounds like the only thing that doesn’t work is something which cannot work as installed.