Horizontal scaling for your custom WebSocket server without relying on sticky sessions by using Redis for session storage and message distribution.

1. Use Redis Pub/Sub to distribute WebSocket messages across multiple server instances. This ensures that messages are delivered to the correct WebSocket client regardless of which instance it is connected to.
2. Store session data in Redis so that any WebSocket server instance can retrieve user connection details dynamically, preventing session stickiness.
3. Implement WebSocket connection handling using FastAPI and aioredis to efficiently manage real-time communication.