diff --git a/flake.nix b/flake.nix
index a7d1c5d..1ee1ae0 100644
--- a/flake.nix
+++ b/flake.nix
@@ -75,7 +75,7 @@
         modules = [
           # Apply the overlay first so pkgs in later modules (like our local
           # `minecraft.nix`) see the extra helpers provided by the overlay
-          { nixpkgs.overlays = [ inputs.nix-minecraft.overlay ]; }
+          {nixpkgs.overlays = [inputs.nix-minecraft.overlay];}
 
           nix-minecraft.nixosModules.minecraft-servers
 
diff --git a/nix-system-configs/modules/system/minecraft.nix b/nix-system-configs/modules/system/minecraft.nix
index 743bded..c120017 100644
--- a/nix-system-configs/modules/system/minecraft.nix
+++ b/nix-system-configs/modules/system/minecraft.nix
@@ -10,7 +10,7 @@
   # Try to use the nix-minecraft helper if the overlay is present; otherwise
   # fall back to a local path. If you use the fallback, ensure the path is an
   # unpacked modpack directory with `mods` and `config` subdirectories.
-  modpack = /srv/minecraft/modpacks/AllTheMods10-prg.mrpack;
+  modpack = /srv/minecraft/modpacks/atm10;
 in {
   options.local = {
     hostname = lib.mkOption {
@@ -70,7 +70,7 @@ in {
       eula = true;
       openFirewall = true;
 
-      servers.all-the-mods-ten-tss = {
+      servers.all-the-mods-tss = {
         enable = true;
         autoStart = true;
         restart = "always";
@@ -78,8 +78,26 @@ in {
         package = pkgs.neoforgeServers.neoforge-1_21_1-21_1_224;
 
         jvmOpts = lib.concatStringsSep " " [
-          "-Xms18G"
+          "-Xms4G"
           "-Xmx45G"
+          "-XX:+UseG1GC"
+          "-XX:+ParallelRefProcEnabled"
+          "-XX:MaxGCPauseMillis=200"
+          "-XX:+UnlockExperimentalVMOptions"
+          "-XX:+DisableExplicitGC"
+          "-XX:+AlwaysPreTouch"
+          "-XX:G1NewSizePercent=30"
+          "-XX:G1MaxNewSizePercent=40"
+          "-XX:G1HeapRegionSize=8M"
+          "-XX:G1ReservePercent=20"
+          "-XX:G1HeapWastePercent=5"
+          "-XX:G1MixedGCCountTarget=4"
+          "-XX:InitiatingHeapOccupancyPercent=15"
+          "-XX:G1MixedGCLiveThresholdPercent=90"
+          "-XX:G1RSetUpdatingPauseTimePercent=5"
+          "-XX:SurvivorRatio=32"
+          "-XX:+PerfDisableSharedMem"
+          "-XX:MaxTenuringThreshold=1"
         ];
 
         serverProperties = {
@@ -97,7 +115,57 @@ in {
           enable-command-block = false;
           enable-rcon = false;
           require-resource-pack = false;
+          level-type = "minecraft:amplified";
           level-seed = "-2032795982907864146";
+
+          # Added properties (do not overwrite existing ones above)
+          accepts-transfers = false;
+          allow-flight = true;
+          allow-nether = true;
+          broadcast-console-to-ops = true;
+          broadcast-rcon-to-ops = true;
+          bug-report-link = "";
+          enable-jmx-monitoring = false;
+          enable-query = false;
+          enable-status = true;
+          enforce-whitelist = false;
+          entity-broadcast-range-percentage = 100;
+          force-gamemode = false;
+          function-permission-level = 2;
+          generate-structures = true;
+          hardcore = false;
+          hide-online-players = false;
+          initial-disabled-packs = "";
+          initial-enabled-packs = "vanilla";
+          level-name = "world";
+          log-ips = true;
+          max-chained-neighbor-updates = 1000000;
+          max-tick-time = 180000;
+          max-world-size = 29999984;
+          network-compression-threshold = 256;
+          op-permission-level = 4;
+          player-idle-timeout = 0;
+          prevent-proxy-connections = false;
+          pvp = true;
+          # dotted keys must be quoted
+          "query.port" = 25566;
+          rate-limit = 0;
+          "rcon.password" = "";
+          "rcon.port" = 25575;
+          region-file-compression = "deflate";
+          resource-pack = "";
+          resource-pack-id = "";
+          resource-pack-prompt = "";
+          resource-pack-sha1 = "";
+          server-ip = "";
+          spawn-animals = true;
+          spawn-monsters = true;
+          spawn-npcs = true;
+          sync-chunk-writes = true;
+          text-filtering-config = "";
+          use-native-transport = true;
+          # white-list, view-distance, simulation-distance, spawn-protection, etc.
+          # were kept above to avoid overwriting existing values.
         };
 
         # Grant operator privileges to the user with the given UUID.
@@ -110,34 +178,20 @@ in {
           };
         };
 
-        #symlinks = {
-        #  "mods" = "${modpack}/overrides/mods";
-        #  "moddata" = "${modpack}/overrides/moddata";
-        #  "resourcepacks" = "${modpack}/overrides/resourcepacks";
-        #  "shaderpacks" = "${modpack}/overrides/shaderpacks";
-        #  "dynamic-resource-pack-cache" = "${modpack}/overrides/dynamic-resource-pack-cache";
-        #  "dynamic-data-pack-cache" = "${modpack}/overrides/dynamic-data-pack-cache";
-        #};
-        #files = {
-        #  "backup" = "${modpack}/overrides/backup";
-        #  "blueprints" = "${modpack}/overrides/blueprints";
-        #  "command_history.txt" = "${modpack}/overrides/command_history.txt";
-        #  "config" = "${modpack}/overrides/config";
-        #  "datapacks" = "${modpack}/overrides/datapacks";
-        #  "downloads" = "${modpack}/overrides/downloads";
-        #  "ESM" = "${modpack}/overrides/ESM";
-        #  "eula.txt" = "${modpack}/overrides/eula.txt";
-        #  "fancymenu_data" = "${modpack}/overrides/fancymenu_data";
-        #  "journeymap" = "${modpack}/overrides/journeymap";
-        #  "kubejs" = "${modpack}/overrides/kubejs";
-        #  "manifest.json" = "${modpack}/overrides/manifest.json";
-        #  "minecraftinstance.json" = "${modpack}/overrides/minecraftinstance.json";
-        #  "observable_announce" = "${modpack}/overrides/observable_announce";
-        #  "options.txt" = "${modpack}/overrides/options.txt";
-        #  "patchouli_books" = "${modpack}/overrides/patchouli_books";
-        #  "patchouli_data.json" = "${modpack}/overrides/patchouli_data.json";
-        #  "schematics" = "${modpack}/overrides/schematics";
-        #};
+        symlinks = {
+          "mods" = "${modpack}/mods";
+          "datapacks" = "${modpack}/datapacks";
+          "user_jvm_args.txt" = "${modpack}/user_jvm_args.txt";
+        };
+        files = {
+          "config" = "${modpack}/config";
+          "patchouli_books" = "${modpack}/patchouli_books";
+          "defaultconfigs" = "${modpack}/defaultconfigs";
+          "kubejs" = "${modpack}/kubejs";
+          "local" = "${modpack}/local";
+          ".mixin.out" = "${modpack}/.mixin.out";
+          "dynamic-data-pack-cache" = "${modpack}/dynamic-data-pack-cache";
+        };
       };
 
       servers.fabric-modded = {
@@ -435,10 +489,32 @@ in {
       };
     };
 
-    # For FastBackup force etc to have PATH
+    # For FastBackup and to force OpenJDK 21 for the Minecraft services,
+    # set JAVA_HOME and include the OpenJDK bin in the service environment.
+    # Add matching environment for both server units created by nix-minecraft.
     systemd.services."minecraft-server-fabric-modded".environment = {
+      JAVA_HOME = lib.mkForce "${pkgs.openjdk21}";
       PATH = lib.mkForce (
         lib.makeBinPath [
+          pkgs.openjdk21
+          pkgs.git
+          pkgs.git-lfs
+          pkgs.coreutils
+          pkgs.findutils
+          pkgs.gnugrep
+          pkgs.gnused
+          pkgs.systemd
+        ]
+        + ":/run/current-system/sw/bin"
+      );
+    };
+
+    # Ensure the other server unit also uses OpenJDK 21
+    systemd.services."minecraft-server-all-the-mods-tss".environment = {
+      JAVA_HOME = lib.mkForce "${pkgs.openjdk21}";
+      PATH = lib.mkForce (
+        lib.makeBinPath [
+          pkgs.openjdk21
           pkgs.git
           pkgs.git-lfs
           pkgs.coreutils