I've stumped upon the same issue , and figured out why .

This issue occurs because Laravel uses a single-threaded request-handling model (in most configurations), meaning that while the SSE endpoint is running and keeping the connection open, Laravel cannot handle other incoming requests. The result is that requests are effectively "blocked" until the SSE process completes.

So basically you have to use Websocket , because it uses a different protocol WS which won't block the HTTP requests that Laravel uses .