"The theoretical limit is 65k connections per IP address"

What's the driving factor for that limitation?

"The TCP protocol provides 16 bits for the port number, and this is interpreted as an unsigned integer; all values are valid, apart from 0, and so the largest port number is (2^16 - 1) or 65,535."

Ah, on the client side not the server, makes sense. I was doing the math as the full IP + port, which would offer 48 bits, but with only one client IP you really only have a client port to play with and you must bind as long as the connection remains open.

> The client side has similar settings but does not need to set up multiple IP addresses, obviously

Also as I know, Linux will only use one IP for outbound connections, unless forcefully bind to another IP address in the code.

The server only uses only one port. 9001 according to the code. https://github.com/uNetworking/uWebSockets.js/blob/875f16e1f...

This blog post does not make any sense.