Internet-Security.com TCP port 10009 details

Lightning Network Daemon (lnd), a Bitcoin Lightning implementation by Lightning Labs, uses TCP port 10009 by default for its gRPC API.
Tools and services such as lncli, Ride The Lightning (RTL), Lightning Terminal (LiT), and BTCPay Server connect to lnd via 127.0.0.1:10009 (or a mapped container port) to manage wallets and channels.
Popular node distributions like Umbrel, RaspiBlitz, and myNode expose or map port 10009 internally for lnd’s RPC interface.

TCP 10009