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.

 

[Patrick9876]

... 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.

Hmm. That's good to know. Thank you. Assuming I configure the two router's DDNS stuff the same then I won't know if its working on the new router. I'd better provide a different name on the new router. Or I could temporarily use a different DDNS service.

... If your first router is ISP provided Gateway - make sure this ISP allows replacing their equipment with your own.

Luckily, both the cable modem and router are my own so replacing the router won't be a problem. I've replaced/upgraded the router twice over the past ten years or so. But this will be my first non-AUSU router (a GL-inet) and my synapses have calcified a bit so I expect configuring is going to take longer than in the past. I want my old router running my network while I'm struggling/playing with the new one.

 

[Tech9]

Assuming I configure the two router's DDNS stuff the same

The reason I mentioned "small exceptions" above. Services like DDNS, UPnP, VPN Server, etc. you can do after you swap the routers. My advice is to configure the new router with the same SSID/password as the old router. Use temporary SSID just for setting up the new router, then switch back to yours. It will save you downtime especially if you have many IoTs. Otherwise you have to reconnect all your wireless clients. With the same SSID/password you may need to forget the connection and reconnect on few devices only.

But this will be my first non-AUSU router (a GL-inet)

GL.iNet routers have very user-friendly interface. Perhaps easier than setting up an ASUS router. Just read the manual and you're good. The Phone App will have your new router going in basic configuration in a minute, WebUI as usual has more settings.

 

[cptnoblivious]

Hmm. That's good to know. Thank you. Assuming I configure the two router's DDNS stuff the same then I won't know if its working on the new router. I'd better provide a different name on the new router. Or I could temporarily use a different DDNS service.
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That's what I've done before, set another DDNS name for the 2nd router, see that it's registering properly. When you do the final router swap, you can clone the external MAC of the router you're replacing and you _should_ keep the same external IP. In case that's important to you, I've not bothered in the past, after all that's why I'm using DDNS in the first place

Good luck!