How to send traffic from an interface to a specific ip-address using a DD-WRT router?

Question

VPN

I have a router with dd-wrt firmware, which is connected to the Internet first to the provider, and then through the OpenVPN client. By default, all traffic goes through the VPN.
I want to make sure that the Internet from the WAN port (ppp0 interface) and not from the VPN (tun0 interface) passes to a device with a specific IP on the local network (server connected by wire, ip: 192.168.1.3). How to do it?
I don't understand iptables, please explain in as much detail as possible.

Answer 1

I think it’s rather not iptables that is needed here, but policy routing. If you have the iproute2 package on dd-wrt, then the following commands will do:
ppp0_gw - gateway address of your ppp0 connection