Issue with downloads that take a while expiring, and failing the build

[Squawkykaka]

When i updated my system and it needed to download a somewhat large closure (1.4Gb) ncro ended up cancelling and failing the download after an amount of time rather than just let it finish

Relevant logs.

structuredAttrs is enabled
structuredAttrs is enabled
copying path '/nix/store/f6lwxgylc8g9c1ygr8gy6prnw8l0nbnd-fastfetch-2.64.2' from 'http://localhost:8080'...
error: some substitutes for the outputs of derivation '/nix/store/qxqd7fdyprml5h5gdni249bfzj0y5y66-openjdk-17.0.20+2.drv' failed (usually happens due to networking issues); try '--fallback' to build derivation from source

my nix config for ncro:

{
  pkgs,
  ...
}:
{
  imports = [
    /home/gleask/documents/projects/public/ncro/nix/module.nix
  ];

  services.ncro = {
    enable = true;
    settings = {
      upstreams = [
        {
          url = "https://cache.nixos.org";
          priority = 10;
        }
        {
          url = "https://nix-community.cachix.org";
          priority = 20;
        }
      ];
    };
  };

  nix.settings.substituters = pkgs.lib.mkForce [ "http://localhost:8080" ];
}

Id expect this to work rather than erroring out