diff --git a/server/src/utils/socketUtils.ts b/server/src/utils/socketUtils.ts
index e5c96f1..9f0780a 100644
--- a/server/src/utils/socketUtils.ts
+++ b/server/src/utils/socketUtils.ts
@@ -29,13 +29,15 @@ export const disconnectUserFromLobby = async (
   reason: string
 ): Promise<boolean> => {
   const sockets = await io.in(lobbyId).fetchSockets();
-  const targetSocket = sockets.find((s: any) => s.data.user?.id === userId);
+  const targetSockets = sockets.filter((s: any) => s.data.user?.id === userId);
 
-  if (!targetSocket) return false;
+  if (targetSockets.length === 0) return false;
 
-  targetSocket.emit('FORCE_DISCONNECT', { lobbyId, reason });
-  io.to(lobbyId).except(targetSocket.id).emit('USER_LEFT', targetSocket.data.user);
-  targetSocket.leave(lobbyId);
+  for (const socket of targetSockets) {
+    socket.emit('FORCE_DISCONNECT', { lobbyId, reason });
+    io.to(lobbyId).except(socket.id).emit('USER_LEFT', socket.data.user);
+    socket.leave(lobbyId);
+  }
 
   return true;
 };
diff --git a/server/test/socket.utils.test.ts b/server/test/socket.utils.test.ts
new file mode 100644
index 0000000..303d2d0
--- /dev/null
+++ b/server/test/socket.utils.test.ts
@@ -0,0 +1,54 @@
+import { describe, it, expect, vi } from 'vitest';
+import { disconnectUserFromLobby } from '../src/utils/socketUtils.js';
+
+describe('socketUtils - disconnectUserFromLobby', () => {
+  it('should disconnect ALL sockets belonging to the same user in a lobby', async () => {
+    const lobbyId = 'lobby-1';
+    const userId = 'user-1';
+    const reason = 'test-reason';
+
+    // Mock sockets
+    const mockSocket1 = {
+      id: 'socket-1',
+      data: { user: { id: userId, username: 'user1' } },
+      emit: vi.fn(),
+      leave: vi.fn(),
+    };
+    const mockSocket2 = {
+      id: 'socket-2',
+      data: { user: { id: userId, username: 'user1' } },
+      emit: vi.fn(),
+      leave: vi.fn(),
+    };
+    const mockSocket3 = {
+      id: 'socket-3',
+      data: { user: { id: 'user-2', username: 'user2' } },
+      emit: vi.fn(),
+      leave: vi.fn(),
+    };
+
+    // Mock IO
+    const mockIo = {
+      in: vi.fn().mockReturnThis(),
+      fetchSockets: vi.fn().mockResolvedValue([mockSocket1, mockSocket2, mockSocket3]),
+      to: vi.fn().mockReturnThis(),
+      except: vi.fn().mockReturnThis(),
+      emit: vi.fn(),
+    };
+
+    const result = await disconnectUserFromLobby(mockIo as any, lobbyId, userId, reason);
+
+    expect(result).toBe(true);
+
+    // We want BOTH mockSocket1 and mockSocket2 to be disconnected
+    expect(mockSocket1.emit).toHaveBeenCalledWith('FORCE_DISCONNECT', { lobbyId, reason });
+    expect(mockSocket1.leave).toHaveBeenCalledWith(lobbyId);
+
+    expect(mockSocket2.emit).toHaveBeenCalledWith('FORCE_DISCONNECT', { lobbyId, reason });
+    expect(mockSocket2.leave).toHaveBeenCalledWith(lobbyId);
+
+    // mockSocket3 should NOT be disconnected
+    expect(mockSocket3.emit).not.toHaveBeenCalled();
+    expect(mockSocket3.leave).not.toHaveBeenCalled();
+  });
+});