Internet-Security.com TCP port 9501 details

TCP 9501 is commonly used by Swoole/OpenSwoole servers to serve HTTP or WebSocket endpoints.
The Hyperf PHP framework listens on 0.0.0.0:9501 by default for its HTTP server (default config).
EasySwoole also defaults to port 9501 for its main server process.
In the wild, many deployments expose a “Swoole http server” banner on port 9501, confirming real-world usage by Swoole-based apps.
There is no widely recognized standard or vendor-assigned protocol for 9501 beyond these Swoole-based frameworks.

TCP 9501