diff --git a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/network/ClientService.java b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/network/ClientService.java
index e6b7643..8fac6f3 100644
--- a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/network/ClientService.java
+++ b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/network/ClientService.java
@@ -80,9 +80,11 @@ public class ClientService {
         return offlineMode;
     }
 
+    // Allow primitive values to contain hyphens (UUIDs) in addition to
+    // digits/words/colons
     static Pattern responseRex =
             Pattern.compile(
-                    "(?<key>\\w+)=(('(?<string>([^']|\\')+)')|(?<primVal>[+-]?[\\d\\w:]+))");
+                    "(?<key>\\w+)=(('(?<string>([^']|\\')+)')|(?<primVal>[+-]?[-\\d\\w:]+))");
 
     /**
      * Removes escape characters from a string, specifically converting escaped single quotes (\')
diff --git a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/gameui/gameuicomponents/TaskbarController.java b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/gameui/gameuicomponents/TaskbarController.java
index 667a584..096ac28 100644
--- a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/gameui/gameuicomponents/TaskbarController.java
+++ b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/gameui/gameuicomponents/TaskbarController.java
@@ -387,9 +387,26 @@ public class TaskbarController {
                     currentStage.close();
                     // Start lobby UI
                     try {
-                        new Casinomainui().start(new javafx.stage.Stage());
+                        javafx.stage.Stage newStage = new javafx.stage.Stage();
+                        javafx.fxml.FXMLLoader fxmlLoader =
+                                new javafx.fxml.FXMLLoader(
+                                        getClass().getResource("/ui-structure/Casinomainui.fxml"));
+                        javafx.scene.Parent root = fxmlLoader.load();
+                        javafx.scene.Scene scene =
+                                new javafx.scene.Scene(
+                                        root, Casinomainui.SCENE_WIDTH, Casinomainui.SCENE_HEIGHT);
+                        newStage.setTitle("Casono");
+                        javafx.scene.image.Image icon =
+                                new javafx.scene.image.Image(
+                                        getClass()
+                                                .getResource("/images/logoinverted.png")
+                                                .toExternalForm());
+                        newStage.getIcons().add(icon);
+                        newStage.setScene(scene);
+                        newStage.setFullScreen(true);
+                        newStage.show();
                     } catch (Exception e) {
-                        LOGGER.error("Error: starting the lobby UI: {}", e.getMessage());
+                        LOGGER.error("Error: starting the lobby UI: {}", e.getMessage(), e);
                     }
                 });
     }
diff --git a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/lobbyui/Casinomainui.java b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/lobbyui/Casinomainui.java
index bb7976c..67415c5 100644
--- a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/lobbyui/Casinomainui.java
+++ b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/client/ui/lobbyui/Casinomainui.java
@@ -19,8 +19,8 @@ public class Casinomainui extends Application {
         // Default constructor
     }
 
-    private static final int SCENE_WIDTH = 1200;
-    private static final int SCENE_HEIGHT = 800;
+    public static final int SCENE_WIDTH = 1200;
+    public static final int SCENE_HEIGHT = 800;
 
     @Override
     /**
diff --git a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/lobby/join_lobby/JoinLobbyHandler.java b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/lobby/join_lobby/JoinLobbyHandler.java
index 579c281..169b027 100644
--- a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/lobby/join_lobby/JoinLobbyHandler.java
+++ b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/lobby/join_lobby/JoinLobbyHandler.java
@@ -9,6 +9,8 @@ import ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandH
 import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.ErrorResponse;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.OkResponse;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.dispatcher.ResponseDispatcher;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
 
 /**
  * Handler for the `JOIN_LOBBY` command.
@@ -21,6 +23,7 @@ import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.dispatch
 public class JoinLobbyHandler extends CommandHandler<JoinLobbyRequest> {
     private final LobbyManager lobbyManager;
     private final UserRegistry userRegistry;
+    private static final Logger LOGGER = LogManager.getLogger(JoinLobbyHandler.class);
 
     /**
      * Create a new {@link JoinLobbyHandler}.
@@ -46,9 +49,17 @@ public class JoinLobbyHandler extends CommandHandler<JoinLobbyRequest> {
      */
     @Override
     public void execute(JoinLobbyRequest request) {
+        LOGGER.info(
+                "JOIN_LOBBY request: session={}, lobbyId={}",
+                request.getContext().sessionId(),
+                request.getId());
         LobbyId lid = LobbyId.of(request.getId());
         var lobby = lobbyManager.getLobby(lid);
         if (lobby == null) {
+            LOGGER.warn(
+                    "JOIN_LOBBY: Lobby {} not found (session={})",
+                    request.getId(),
+                    request.getContext().sessionId());
             responseDispatcher.dispatch(
                     new ErrorResponse(request.getContext(), "LOBBY_NOT_FOUND", "Lobby not found"));
             return;
@@ -56,7 +67,9 @@ public class JoinLobbyHandler extends CommandHandler<JoinLobbyRequest> {
 
         var maybeUser = userRegistry.getBySessionId(request.getContext().sessionId());
         if (maybeUser.isEmpty()) {
-            // UserLoggedInCheck should normally prevent this; keep safe fallback
+            LOGGER.warn(
+                    "JOIN_LOBBY: No user associated with session {}",
+                    request.getContext().sessionId());
             responseDispatcher.dispatch(
                     new ErrorResponse(
                             request.getContext(),
@@ -70,6 +83,10 @@ public class JoinLobbyHandler extends CommandHandler<JoinLobbyRequest> {
 
         boolean ok = lobbyManager.addPlayerToLobby(username, lid);
         if (!ok) {
+            LOGGER.warn(
+                    "JOIN_LOBBY: User '{}' failed to join lobby {} (full or already in)",
+                    username,
+                    request.getId());
             responseDispatcher.dispatch(
                     new ErrorResponse(
                             request.getContext(),
@@ -78,6 +95,8 @@ public class JoinLobbyHandler extends CommandHandler<JoinLobbyRequest> {
             return;
         }
 
+        LOGGER.info("User '{}' joined lobby {}", username, request.getId());
+
         responseDispatcher.dispatch(new OkResponse(request.getContext()));
     }
 }
diff --git a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/domain/lobby/LobbyManager.java b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/domain/lobby/LobbyManager.java
index 2179e8a..515aee4 100644
--- a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/domain/lobby/LobbyManager.java
+++ b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/domain/lobby/LobbyManager.java
@@ -69,6 +69,15 @@ public class LobbyManager {
                 lobby.addPlayerAndMaybeStart(
                         username, maxPlayersPerLobby, AUTO_START_PLAYERS, DEFAULT_START_CHIPS);
         if (result != AddResult.NOT_ADDED) {
+            LOGGER.info(
+                    () ->
+                            "User '"
+                                    + username
+                                    + "' joined lobby "
+                                    + lobbyId.value()
+                                    + " (result="
+                                    + result
+                                    + ")");
             playerToLobby.put(username, lobbyId);
             if (result == AddResult.ADDED_AND_STARTED) {
                 LOGGER.info(