I have two network interfaces on my Freepbx 13 server. Both of them have static ip adresses (first - public, second - local). Some clients must connect from the Internet, others - from local subnets. What type of IP configuration would be better to choose in the Chan SIP Settings: “Static IP” or “Public IP” ?
You need to choose the Static IP and configure your local networks as well.
In a case that you have 2 gateways to reach for, set the public one as your default gateway and add a static route
to your local network through the local interface in the Linux operating system.