How to configure internet for one 'super' router and four routers underneat

Question

In our home we have one Ziggo (dutch cable internet provider) router and we are stuck with one unfortunately.
However, as we have 4 households (appartements) that all should connect to this router, we wish to all have our own router and subnet so we can't access each others devices. Now I was wondering, how would you configure the subnets and the DHCP on each device? I was thinking of creating a different DHCP range for each router (as the main router doesn't need to know about the DHCP setup on the household routers)

Would love to hear your opinion :)

Answer 1

This is entirely possible:

By default most routers have DHCP enabled. Just connect each of them from their WAN-Port to one of the LAN-Ports on the Main Router.

The specific DHCP-Range of each of those routers does not matter (exception: see next paragraph) and even having the same range for the 4 routers should not be a problem since those routers are not aware of what is going on behind the other 3 routers (but having multiple ranges might make it easier to distinguish to which of the networks they are connected if some users use more than one of these networks).

I'm not entirely sure if this is necessary but from my understanding the DHCP Range of the Main Router should be different from the DHCP Range of the other 4 routers (even though those 4 can be the same). If this is not the case the "Sub-Routers" might be confused which network is talking to them.

This picture shows a mixture of both having different and the same DHCP Ranges on the sub-routers: Routers #2 and #3 both feature range 192.168.20.0/24 (192.168.20.1 - 192.168.20.255) but they are not shared between both routers. Devices on Router #2 can still not see devices on Router #3 and both routers will asssign the IPs independently.

I use two routers "in series" myself since I need the router supplied by my ISP but need additional flexibility that my ISPs router doesn't offer.

Additional Information that might add a second option to your situation:

I don't need multiple routers but I have multiple VLANs (Virtual LANs; with different DHCP ranges) that prevent devices from talking from one VLAN to another (one VLAN for my own devices, one for guests etc.). I don't know the specific situation you are in but if the networks are managed by one person only anyway and privacy is not to big of a concern you could also add just one "high end" router and then add multiple VLANs and use a managed switch to split them up for the different households. Buying one good router, a managed switch and four (or potentially less; you might be able to have multiple SSIDs/ Wifi-names per access point) access points could actually turn out cheaper but this depends heavily on your specific situation.

Answer 2

You can accomplish what you wish to do.

For each sub-router:

Hook up the WAN port to a LAN port on the Main Network. Make sure the DHCP is enabled in the LAN section of each sub-router (that is normally the default way). Make an IP Range for each sub-router. The exact IP range does not really matter - it can be different for organizational purposes.

Done this way, users on one sub-router cannot see users on another sub-router.

I have done this both ways in my setups here.