How to bring Internet to a DD-WRT router from another router?

I have a new Internet connection that came with a preconfigured modem-router. That works really well but it has only 2 ethernet port and no wireless. So I would like to connect my other router running DD-WRT to connect all my wired and wireless devices.

My issue is that I don't really understand what mode I have to chose for my DD-WRT router. Should I bridge or repeat the network?

I am confused and I would really appreciate some help with that! Also I want to precise that I only want to use the routing functionality of the DD-WRT router because the ISP modem router is extremely basic and does allow any configuration...

Here is a schema of the desired network:

Thanks!

Solution 1:

That link is about repeating an existing wireless signal to extend its range. You just want the default settings on the router, and you just plug it in as you have described and it will play.

In your diagram you show two different networks ( 192.168.1.x and 192.168.2.x ), but nothing other than the router on the first network. This is effectively what you will have if you connect the modem to the wan port of the router, and change the address of the router from 192.168.1.1 to 192.168.2.1. There is really no need to do that though, and in fact, if you want to plug a computer into the second port on the modem and have it speak with the rest of your devices, you don't want to do it that way. Don't use the WAN port on the router, disable the DHCP service on the router, and all of the computers, no matter which device they are plugged into, will get their IP address from the modem and be able to see each other.