How to set up network routing in Asterisk?

Question

Asterisk

There is a firewall in the form of PFsense. It connects via OpenVPN.
But through VPN there is no access to asterisk, which has its own external interface. There is access from the VPN network to other computers.
When tracing a VPN network from an asterisk, it sends packets to the external interface.
Tell me, where is network routing configured in asterisk?