Override SoftetherVPN version

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1

I am trying to test different versions of softether vpn and running into some weird issues.
I am relatively new to nixos and could use some help.

I have been able to install softether and connect using the default options, but the speed was very slow. 5-8 Mbps download. (Compared to a P4 era pc with 4.08.9449 which was getting 96.4 Mbps)

So far I have tried:
4.41-9782-beta [5.27 Mbps] (current default version from nixos)
4.38-9760-rtm [6.45 Mbps]
5.02.5187 [8.07 Mbps] (latest dev version)

The weirdness I am running into is with the software version displaying (and slow speeds).
On the server when I run “systemctl status vpnserver” I get the correct software versions in the output:

Process: 988 ExecStart=/nix/store/kbin6338payvrgx4kfwvygb96kjaar3k-softether-**5.02.5187**/bin/vpnserver start (code=exited, status=0/SUCCESS)

 Process: 4164 ExecStart=/nix/store/1kv16dqirk561b55fq2f9fpap5j8lyfp-softether-**4.38-9760-rtm**/bin/vpnserver start (code=exited, status=0/SUCCESS)

When connecting from the client and viewing connection status it shows server version 4.41 build 9782 (the initial and default install package).
When connecting from the GUI server manager and clicking the “About this VPN Server” button it also displays the 4.41 build 9782.

It seems like the server does not recognize the newer installs and properly change the software version.

Example config used to override the version. Am I doing something completely wrong?

  networking.firewall.enable = true;
  networking.firewall.allowedTCPPorts = [ 443 992 1194 5555 ];
  networking.firewall.allowedUDPPorts = [ 500 4500 ];

  # Override SoftetherVPN version
  nixpkgs.overlays = [ (self: super: {
          softether = super.softether.overrideAttrs (old: {
              version = "4.38-9760-rtm";
              src = old.src.overrideAttrs {
                sha256 = "";
                };
            });
      }) ];

  # Test Dev Version
  /*
  nixpkgs.overlays = [ (self: super: {
          softether = super.softether.overrideAttrs (old: {
              version = "5.02.5187";
              src = old.src.overrideAttrs {
                repo = "SoftEtherVPN";
                tag = "5.02.5187";
                sha256 = "";
                };
            });
      }) ];
  */

  # Install softether vpn
  environment.systemPackages = with pkgs; [
  	softether
  ];

  # Enable VPN Server
  services.softether.enable = true;
  services.softether.vpnserver.enable = true;