connect LAN to Wan through VPN

hi guys . i have RB750

i have connected my LAN to port1 with DHCP enabled and 192.168.1.0 network

and i have a modem connected to intranet on port 3 with 192.168.3.0 network

and i have enabled a pppoe client and a hotspot on port 5 . hot spot works fine .

i want to connect whole lan to intranet network with vpn and when it is disconnected the internet on hotspot .


hotspot is ok . how can i configure it to connect to intranet network on port 3 when connecting to VPN??/