how to control homekit apple with mikrotik vpn

raspberry pi is my core of apple homekits. all of my Nodemcu are connected to my accespoint and they are connected to raspberry pi with MQTT for pub and sub payload msg.
all of my devicess in the same dhcp server. all etheres ports are in the bridge.
my l2tp vpn server setup in the same dhcp and vpn set it at the same pool dhcp, but in home app it show not available .
how can i make it work ?