How to decide which network interface a socket is listen on?

[axellin]

Hi,

My device is running as an AP (mainly for configuration) and also running pppos to reach internet.
I'm wondering when start a tcp server listen on a given port, which interface the socket is listen on?
Can I decide which interface to listen on?
It does not make sense to listen on the ppp interface, so I'd like to just make my tcp server only
listen on either AP or STA interface.
My tcp server seems does not work if started pppos, but it works fine without starting pppos.

BTW, I hit some problems when start AP/STA and pppos at the same time.
see https://github.com/espressif/esp-idf/issues/4634
Appreciate if someone can help.