Daisy-chaining routers?

[Patrick9876]

I know nothing about the WAN connection between, for instance, a cable modem and a router so this may be a stupid question. Can I put a 2nd router on a LAN port of a 1st router? I'm probably going to soon buy a new router and am anticipating a fairly long learning curve in the configuring process ... especially if I decide to use OpenWrt.
Once configured and tested it will have it's WAN port connected to my cable modem. This is just a temporary configuration.

It would be very convenient to have that router just be another device on my LAN. I will obviously need to have different SSIDs for the WiFi config. And when I set up DDNS on the new router it will advertise a meaningless and unreachable (LAN) address. Those I can cope with. Are there other things I need to be aware of that would may this problematic or impossible?

 

[ColinTaylor]

Can I put a 2nd router on a LAN port of a 1st router?

Yes. This is quite common, especially during the commissioning of a new router. Just make sure that the 2nd router's LAN subnet is different than the primary router's.

And when I set up DDNS on the new router it will advertise a meaningless and unreachable (LAN) address.

Probably not. I don't know about OpenWrt specifically, but a DDNS client will usually determine your external (public) IP address and register that rather than relying on the IP address of the WAN interface.

 

[Tech9]

Can I put a 2nd router on a LAN port of a 1st router?

Yes. It will most likely be in double NAT configuration (or not, some ISP Gateways offer passthrough ports), but you can pre-configure your new network there (with small exceptions) and just remove the old router when ready. The second router has to have LAN IP on different subnet than the first. If your first router is ISP provided Gateway - make sure this ISP allows replacing their equipment with your own.