Assign interface for one/few devices

Installing and Using OpenWrt
1

Hi everyone)
Please suggest or direct where you can view/ask the following:

  1. There are several interfaces. One interface is a PPTP connection (which goes through the Wan). How can I arrange for the PPTP interface to be assigned only for one/few devices (by MAC/IP)?
  2. Is it possible for this interface (PPTP) to start automatically when the necessary devices are connected? (And, accordingly, turned off when they were unavailable).

Thanks in advance for your answers!

2

You can use PBR for this purpose.
https://openwrt.org/docs/guide-user/network/routing/pbr

Keep in mind, PPTP is not secure and should not be used if there are any other alternatives. It is trivially easy to crack and thus considered unsuitable for use on the internet.